Origins

Bactria was inhabited by Greek settlers since the times of Darius I, when the entire population of Barca, in Cyrenaica, was deported to the region for refusing to surrender assassins.^[10] Greek influence increased under Xerxes I, after the descendants of Greek priests who had once lived near Didyma (western Asia Minor) were forcibly relocated in Bactria,^[11] and later on with other exiled Greeks, most of them prisoners of war. Greeks communities and language were already common in the area by the time that Alexander the Great conquered Bactria in 328 BC.^[12]

Independence and Diodotid dynasty

Gold coin of Diodotus c. 245 BC. The Greek inscription reads: ΒΑΣΙΛΕΩΣ ΔΙΟΔΟΤΟΥ – "(of) King Diodotus".

Diodotus, the satrap of Bactria (and probably the surrounding provinces) founded the Greco-Bactrian Kingdom when he seceded from the Seleucid Empire around 250 BC and became King Diodotus I of Bactria. The preserved ancient sources (see below) are somewhat contradictory, and the exact date of Bactrian independence has not been settled. Somewhat simplified, there is a high chronology (c. 255 BC) and a low chronology (c. 246 BC) for Diodotos' secession.^[13] The high chronology has the advantage of explaining why the Seleucid king Antiochus II issued very few coins in Bactria, as Diodotos would have become independent there early in Antiochus' reign.^[14] On the other hand, the low chronology, from the mid-240s BC, has the advantage of connecting the secession of Diodotus I with the Third Syrian War, a catastrophic conflict for the Seleucid Empire.

Diodotus, the governor of the thousand cities of Bactria (Latin: Theodotus, mille urbium Bactrianarum praefectus), defected and proclaimed himself king; all the other people of the Orient followed his example and seceded from the Macedonians.^[15]

The new kingdom, highly urbanized and considered one of the richest of the Orient (opulentissimum illud mille urbium Bactrianum imperium "The extremely prosperous Bactrian empire of the thousand cities", according to Justin^[16]), was to further grow in power and engage in territorial expansion to the east and the west:

Corinthian capital, found at Ai-Khanoum, 2nd century BC

The Greeks who caused Bactria to revolt grew so powerful on account of the fertility of the country that they became masters, not only of Ariana, but also of India, as Apollodorus of Artemita says: and more tribes were subdued by them than by Alexander… Their cities were Bactra (also called Zariaspa, through which flows a river bearing the same name and emptying into the Oxus), and Darapsa, and several others. Among these was Eucratidia,^[17] which was named after its ruler.^[18]

In 247 BC, the Ptolemaic empire (the Greek rulers of Egypt following the death of Alexander the Great) captured the Seleucid capital, Antioch. In the resulting power vacuum, Andragoras, the Seleucid satrap of Parthia, proclaimed independence from the Seleucids, declaring himself king. A decade later, he was defeated and killed by Arsaces of Parthia, leading to the rise of a Parthian Empire. This cut Bactria off from contact with the Greek world. Overland trade continued at a reduced rate, while sea trade between Greek Egypt and Bactria developed.

Diodotus was succeeded by his son Diodotus II, who allied himself with the Parthian Arsaces in his fight against Seleucus II:

Soon after, relieved by the death of Diodotus, Arsaces made peace and concluded an alliance with his son, also by the name of Diodotus; some time later he fought against Seleucos who came to punish the rebels, and he prevailed: the Parthians celebrated this day as the one that marked the beginning of their freedom.^[19]

Euthydemid dynasty and Seleucid invasion

-200

GRECO
BACTRIANS

PAR-
THIA

SAKAS

Korgantas

Sargat

Pazyryk

Tagar

Sagly

Chandman

Shule

Khotan

Sha-
jing

DONGHU

SABEANS

Ordos
culture

Dian
culture

JIN

YUEZHI

Subeshi

Wusun

SELEUCID
EMPIRE

MAURYA
EMPIRE

HAN
DYNASTY

XIONGNU

PTOLE-
MIES

MEROË

Scythians

Sarma-
tians

◁ ▷

Asia in 200 BC, showing the Greco-Bactrian Kingdom and its neighbors

Coin depicting the Greco-Bactrian king Euthydemus 230–200 BC. The Greek inscription reads: ΒΑΣΙΛΕΩΣ ΕΥΘΥΔΗΜΟΥ – "(of) King Euthydemus".

Euthydemus, a Greek from Magnesia according to Polybius,^[20][21] and possibly satrap of Sogdiana, overthrew the dynasty of Diodotus II around 230–220 BC and started his own dynasty. Euthydemus's control extended to Sogdiana, going beyond the city of Alexandria Eschate founded by Alexander the Great in Ferghana:

And they also held Sogdiana, situated above Bactriana towards the east between the Oxus River, which forms the boundary between the Bactrians and the Sogdians, and the Iaxartes River. And the Iaxartes forms also the boundary between the Sogdians and the nomads.^[22]

Euthydemus was attacked by the Seleucid ruler Antiochus III around 210 BC. Although he commanded 10,000 horsemen, Euthydemus initially lost a battle on the Arius^[23] and had to retreat. He then successfully resisted a three-year siege in the fortified city of Bactra (modern Balkh), before Antiochus finally decided to recognize the new ruler, and to offer one of his daughters to Euthydemus's son Demetrius around 206 BC.^[24] Classical accounts also relate that Euthydemus negotiated peace with Antiochus III by suggesting that he deserved credit for overthrowing the original rebel Diodotus and that he was protecting Central Asia from nomadic invasions thanks to his defensive efforts:

... for if he did not yield to this demand, neither of them would be safe: Seeing that great hordes of Nomads were close at hand, who were a danger to both; and that if they admitted them into the country, it would certainly be utterly barbarised.^[21]

In an inscription found in the Kuliab area of Tajikistan, in eastern Greco-Bactria, and dated to 200–195 BC,^[25] a Greek by the name of Heliodotos, dedicating a fire altar to Hestia, mentions Euthydemus as the greatest of all kings, and his son Demetrius I as "Demetrios Kalinikos" "Demetrius the Glorious Conqueror":^[26][25]

Heliodotos inscription, Kuliab

Translation (English)	"Heliodotos dedicated this fragrant altar for Hestia, venerable goddess, illustrious amongst all, in the grove of Zeus, with beautiful trees; he made libations and sacrifices so that the greatest of all kings Euthydemos, as well as his son, the glorious, victorious and remarkable Demetrios, be preserved of all pains, with the help of Tyche with divine thoughts."[27][28]
Transcription (original Greek script)	τόνδε σοι βωμὸν θυώδη, πρέσβα κυδίστη θεῶν Ἑστία, Διὸς κ(α)τ᾽ ἄλσος καλλίδενδρον ἔκτισεν καὶ κλυταῖς ἤσκησε λοιβαῖς ἐμπύροις Ἡλιόδοτος ὄφρα τὸμ πάντων μέγιστον Εὐθύδημον βασιλέων τοῦ τε παῖδα καλλίνικον ἐκπρεπῆ Δημήτριον πρευμενὴς σώιζηις ἐκηδεῖ(ς) σὺν τύχαι θεόφρον[ι]
Inscription (Greek language)

Following the departure of the Seleucid army, the Bactrian kingdom seems to have expanded. In the west, areas in north-eastern Iran may have been absorbed, possibly as far as into Parthia, whose ruler had been defeated by Antiochus the Great. These territories possibly are identical with the Bactrian satrapies of Tapuria and Traxiane.

Expansion into the Indian subcontinent (after 180 BC)

Silver coin depicting Demetrius I of Bactria (reigned c. 200–180 BC), wearing an elephant scalp, symbol of his conquests in northwest Indian subcontinent.

Bactrian phalera with military elephant carrying a howdah fortress manned by a soldier wearing a Macedonian helmet. 2nd century BCE, Hermitage Museum.^[29][30][31]

Demetrius, the son of Euthydemus, started an invasion of the subcontinent from 180 BC, a few years after the Mauryan empire had been overthrown by the Shunga dynasty. Historians differ on the motivations behind the invasion. Some historians suggest that the invasion of the subcontinent was intended to show their support for the Mauryan empire, and to protect the Buddhist faith from the religious persecutions of the Shungas as alleged by Buddhist scriptures (Tarn). Other historians have argued however that the accounts of these persecutions have been exaggerated (Thapar, Lamotte).

Demetrius may have been as far as the imperial capital Pataliputra in today's eastern India (today Patna). However, these campaigns are typically attributed to Menander. The invasion was completed by 175 BC. This established in the northwestern Indian Subcontinent what is called the Indo-Greek Kingdom, which lasted for almost two centuries until around 10 AD. The Buddhist faith flourished under the Indo-Greek kings, foremost among them Menander I. It was also a period of great cultural syncretism, exemplified by the development of Greco-Buddhism.

Eucratides

Back in Bactria, Eucratides, either a general of Demetrius or an ally of the Seleucids, managed to overthrow the Euthydemid dynasty and establish his own rule around 170 BC, probably dethroning Antimachus I and Antimachus II. The Indian branch of the Euthydemids tried to strike back. An Indian king called Demetrius (very likely Demetrius II) is said to have returned to Bactria with 60,000 men to oust the usurper, but he apparently was defeated and killed in the encounter:

Silver tetradrachm of King Eucratides I 171–145 BC. The Greek inscription reads: ΒΑΣΙΛΕΩΣ ΜΕΓΑΛΟΥ ΕΥΚΡΑΤΙΔΟΥ – "(of) King Great Eucratides".

Bilingual coin of Eucratides in the Indian standard, on the obverse Greek inscription reads: ΒΑΣΙΛΕΩΣ ΜΕΓΑΛΟΥ ΕΥΚΡΑΤΙΔΟΥ – "(of) King Great Eucratides", Pali in the Kharoshthi script on the reverse.

Eucratides led many wars with great courage, and, while weakened by them, was put under siege by Demetrius, king of the Indians. He made numerous sorties, and managed to vanquish 60,000 enemies with 300 soldiers, and thus liberated after four months, he put India under his rule.^[32]

Eucratides campaigned extensively in present-day northwestern India, and ruled a vast territory, as indicated by his minting of coins in many Indian mints, possibly as far as the Jhelum River in Punjab. In the end, however, he was repulsed by the Indo-Greek king Menander I, who managed to create a huge unified territory.

In a rather confused account, Justin explains that Eucratides was killed on the field by "his son and joint king", who would be his own son, either Eucratides II or Heliocles I (although there are speculations that it could have been his enemy's son Demetrius II). The son drove over Eucratides' bloodied body with his chariot and left him dismembered without a sepulchre:

As Eucratides returned from India, he was killed on the way back by his son, whom he had associated to his rule, and who, without hiding his parricide, as if he didn't kill a father but an enemy, ran with his chariot over the blood of his father, and ordered the corpse to be left without a sepulture.^[32]

Defeats by Parthia

During or after his Indian campaigns, Eucratides was attacked and defeated by the Parthian king Mithridates I, possibly in alliance with partisans of the Euthydemids:

Gold 20 stater of Eucratides, the largest gold coin of Antiquity. The coin weighs 169.2 grams, and has a diameter of 58 millimeters.

The Bactrians, involved in various wars, lost not only their rule but also their freedom, as, exhausted by their wars against the Sogdians, the Arachotes, the Dranges, the Arians and the Indians, they were finally crushed, as if drawn of all their blood, by an enemy weaker than them, the Parthians.^[32]

Following his victory, Mithridates I gained Bactria's territory west of the Arius, the regions of Tapuria and Traxiane: "The satrapy Turiva and that of Aspionus were taken away from Eucratides by the Parthians."^[22]

In the year 141 BC, the Greco-Bactrians seem to have entered in an alliance with the Seleucid king Demetrius II to fight again against Parthia:

The people of the Orient welcomed his (Demetrius II's) arrival, partly because of the cruelty of the Arsacid king of the Parthians, partly because, used to the rule of the Macedonians, they disliked the arrogance of this new people. Thus, Demetrius, supported by the Persians, Elymes and Bactrians, routed the Parthians in numerous battles. At the end, deceived by a false peace treaty, he was taken prisoner.^[33]

The 5th century historian Orosius reports that Mithridates I managed to occupy territory between the Indus and the Hydaspes towards the end of his reign (c. 138 BC, before his kingdom was weakened by his death in 136 BC).^{[lower-alpha 2]}

Heliocles I ended up ruling what territory remained. The defeat, both in the west and the east, may have left Bactria very weakened and open to nomadic invasions.

Nomadic invasions

The migrations of the Yuezhi through Central Asia, from around 176 BC to AD 30

A nomadic steppe people called the Yuezhi inhabited a region thousands of miles to the east of Bactria on the edges of the Han Empire called the Hexi Corridor. Shortly before 176 BC, the Xiongnu invaded the Hexi Corridor, forcing the Yuezhi to flee the region. In 162 BC the Yuezhi were driven west to the Ili River valley by the Xiongnu. In 132 they were driven out of the Ili valley by the Wusun. The surviving Yuezhi migrated again south towards the territory just north of the Oxus River where they encountered and expelled a nomadic steppe nation called Sakastan.^[34]

Gold artefacts of the Scythians in Bactria, at the site of Tillia tepe

Around 140 BC, eastern Scythians (the Saka, or Sacaraucae of Greek sources), apparently being pushed forward by the southward migration of the Yuezhi started to invade various parts of Parthia and Bactria. Their invasion of Parthia is well documented: they attacked in the direction of the cities of Merv, Hecatompolis and Ecbatana. They managed to defeat and kill the Parthian king Phraates II, son of Mithridates I, routing the Greek mercenary troops under his command (troops he had acquired during his victory over Antiochus VII). Again in 123 BC, Phraates's successor, his uncle Artabanus I, was killed by the Scythians.^[35]

When the Han Chinese diplomat Zhang Qian visited the Yuezhi in 126 BC, trying to obtain their alliance to fight the Xiongnu, he explained that the Yuezhi were settled north of the Oxus but also held under their sway the territory south of Oxus, which makes up the remainder of Bactria.

According to Zhang Qian, the Yuezhi represented a considerable force of between 100,000 and 200,000 mounted archer warriors,^{[lower-alpha 3]} with customs identical to those of the Xiongnu, which would probably have easily defeated Greco-Bactrian forces (in 208 BC when the Greco-Bactrian king Euthydemus I confronted the invasion of the Seleucid king Antiochus III the Great, he commanded 10,000 horsemen).^[23] Zhang Qian actually visited Bactria (named Daxia in Chinese) in 126 BC, and portrays a country which was totally demoralized and whose political system had vanished, although its urban infrastructure remained:

Daxia (Bactria) is located over 2,000 li southwest of Dayuan, south of the Gui (Oxus) river. Its people cultivate the land and have cities and houses. Their customs are like those of Dayuan. It has no great ruler but only a number of petty chiefs ruling the various cities. The people are poor in the use of arms and afraid of battle, but they are clever at commerce. After the Great Yuezhi moved west and attacked Daxia, the entire country came under their sway. The population of the country is large, numbering some 1,000,000 or more persons. The capital is called the city of Lanshi (Bactra) and has a market where all sorts of goods are bought and sold. (Records of the Great Historian by Sima Qian, quoting Zhang Qian, trans. Burton Watson)

The Yuezhi further expanded southward into Bactria around 120 BC, apparently further pushed out by invasions from the northern Wusun. It seems they also pushed Scythian tribes before them, which continued to India, where they came to be identified as Indo-Scythians.

Silver coin of Heliocles (r. 150–125 BC), the last Greco-Bactrian king. The Greek inscription reads: ΒΑΣΙΛΕΩΣ ΔΙΚΑΙΟΥ ΗΛΙΟΚΛΕΟΥΣ – "(of) King Heliocles the Just".

The invasion is also described in western Classical sources from the 1st century BC:

The best known tribes are those who deprived the Greeks of Bactriana, the Asii, Pasiani, Tochari, and Sacarauli, who came from the country on the other side of the Jaxartes, opposite the Sacae and Sogdiani.^[37]

Around that time the king Heliocles abandoned Bactria and moved his capital to the Kabul valley, from where he ruled his Indian holdings. Having left the Bactrian territory, he is technically the last Greco-Bactrian king, although several of his descendants, moving beyond the Hindu Kush, would form the western part of the Indo-Greek kingdom. The last of these "western" Indo-Greek kings, Hermaeus, would rule until around 70 BC, when the Yuezhi again invaded his territory in the Paropamisadae (while the "eastern" Indo-Greek kings would continue to rule until around AD 10 in the area of the Punjab region).

Overall, the Yuezhi remained in Bactria for more than a century. They became Hellenized to some degree, as suggested by their adoption of the Greek alphabet to write their later Iranian court language,^[38][39] and by numerous remaining coins, minted in the style of the Greco-Bactrian kings, with the text in Greek.

Around 12 BC the Yuezhi then moved further to northern India where they established the Kushan Empire.

Greek culture in Bactria

Reconstruction of Kampyr Tepe (Alexandria Oxiana) end 4th cent BCE-1st cent CE. Termez Archaeological Museum.

Greeks first began settling the region long before Alexander conquered it. The Persian Empire had a policy of exiling rebelling Greek communities to that region long before it fell to Greek conquest. Therefore, it had a considerable Greek community that was expanded upon after Macedonian conquest.

The Greco-Bactrians were known for their high level of Hellenistic sophistication, and kept regular contact with both the Mediterranean and neighbouring India. They were on friendly terms with India and exchanged ambassadors.

Their cities, such as Ai-Khanoum in northeastern Afghanistan (probably Alexandria on the Oxus), and Bactra (modern Balkh) where Hellenistic remains have been found, demonstrate a sophisticated Hellenistic urban culture. This site gives a snapshot of Greco-Bactrian culture around 145 BC, as the city was burnt to the ground around that date during nomadic invasions and never re-settled. Ai-Khanoum "has all the hallmarks of a Hellenistic city, with a Greek theater, gymnasium and some Greek houses with colonnaded courtyards" (Boardman). Remains of Classical Corinthian columns were found in excavations of the site, as well as various sculptural fragments. In particular a huge foot fragment in excellent Hellenistic style was recovered, which is estimated to have belonged to a 5–6 meter tall statue.

Stone block with the inscriptions of Kineas in Greek. Ai Khanoum.

One of the inscriptions in Greek found at Ai-Khanoum, the Herôon of Kineas, has been dated to 300–250 BC, and describes Delphic precepts:

As children, learn good manners.
As young men, learn to control the passions.
In middle age, be just.
In old age, give good advice.
Then die, without regret.

Some of the Greco-Bactrian coins, and those of their successors the Indo-Greeks, are considered the finest examples of Greek numismatic art with "a nice blend of realism and idealization", including the largest coins to be minted in the Hellenistic world: the largest gold coin was minted by Eucratides (reigned 171–145 BC), the largest silver coin by the Indo-Greek king Amyntas Nikator (reigned c. 95–90 BC). The portraits "show a degree of individuality never matched by the often bland depictions of their royal contemporaries further West" (Roger Ling, "Greece and the Hellenistic World").

Several other Greco-Bactrian cities have been further identified, as in Saksanokhur in southern Tajikistan (archaeological searches by a Soviet team under B.A. Litvinski),^[42] or in Dal'verzin Tepe.

• 
  Bronze Herakles statuette. Ai Khanoum. 2nd century BC.
• 
  Sculpture of an old man, possibly a philosopher. Ai Khanoum, 2nd century BC.
• 
  Close-up of the same statue.
• 
  Frieze of a naked man wearing a chlamys. Ai Khanoum, 2nd century BC.
• 
  Gargoyle in the form of a Greek comic mask. Ai Khanoum, 2nd century BC.
• 
  Plate depicting Cybele pulled by lions. Ai Khanoum.

Contacts with the Han Empire

Possible statuette of a Greek hoplite, wearing a version of the Greek Phrygian helmet, from a 3rd century BC burial site north of the Tian Shan, Xinjiang Region Museum, Ürümqi.^[46]

To the north, Euthydemus also ruled Sogdiana and Ferghana, and there are indications that from Alexandria Eschate the Greco-Bactrians may have led expeditions as far as Kashgar and Ürümqi in Xinjiang, leading to the first known contacts between China and the West around 220 BC. The Greek historian Strabo too writes that: "they extended their empire even as far as the Seres (Chinese) and the Phryni". (Strabo, XI.XI.I).^[18]

Several statuettes and representations of Greek soldiers have been found north of the Tian Shan, on the doorstep to China, and are today on display in the Xinjiang museum at Ürümqi (Boardman).^{[lower-alpha 4]} Middle Eastern or Greek influences on Chinese art have also been suggested (Hirth, Rostovtzeff). Designs with rosette flowers, geometric lines, meanders and glass inlays, suggestive of Egyptian, Persian, and/or Hellenistic influences,^{[lower-alpha 5]} can be found on some early Han dynasty bronze mirrors.^{[lower-alpha 6]}

Some speculate that Greek influence is found in the artworks of the burial site of China's first Emperor Qin Shi Huang, dating back to the 3rd century BC, including in the manufacture of the famous Terracotta army. This idea suggested that Greek artists may have come to China at that time to train local artisans in making sculptures^[49][50] However, this idea is disputed.^[51]

Numismatics also suggest that some technology exchanges may have occurred on these occasions: the Greco-Bactrians were the first in the world to issue cupro-nickel (75:25 ratio) coins,^[52] an alloy technology only known by the Chinese at the time under the name "White copper" (some weapons from the Warring States period were in copper-nickel alloy).^[53] The practice of exporting Chinese metals, in particular iron, for trade is attested around that period. Kings Euthydemus, Euthydemus II, Agathocles and Pantaleon made these coin issues around 170 BC. An alternative suggestion is that the metal in the coinage derived from a mine where a cupro-nickel alloy occurred naturally, perhaps Anarak in eastern Iran.^[54] Copper-nickel would not be used again in coinage until the 19th century.

The presence of Chinese people in India from ancient times is also suggested by the accounts of the "Ciñas" in the Mahabharata and the Manu Smriti. The Han dynasty explorer and ambassador Zhang Qian visited Bactria in 126 BC, and reported the presence of Chinese products in the Bactrian markets:

"When I was in Bactria (Daxia)", Zhang Qian reported, "I saw bamboo canes from Qiong and cloth made in the province of Shu (territories of southwestern China). When I asked the people how they had gotten such articles, they replied, "Our merchants go buy them in the markets of Shendu (India)." (Shiji 123, Sima Qian, trans. Burton Watson).

Map of the world in 200 BC showing the Han dynasty, the Greco-Bactrian Kingdom, the Maurya Empire and the Yuezhi (Kushans)

The purpose of Zhang Qian's journey was to look for civilizations on the steppe that the Han could ally with against the Xiongnu. Upon his return, Zhang Qian informed the Chinese emperor Han Wudi of the level of sophistication of the urban civilizations of Ferghana, Bactria and Parthia, who became interested in developing commercial relationships with them:

The Son of Heaven on hearing all this reasoned thus: Ferghana (Dayuan) and the possessions of Bactria (Daxia) and Parthia (Anxi) are large countries, full of rare things, with a population living in fixed abodes and given to occupations somewhat identical with those of the Chinese people, and placing great value on the rich produce of China. (Hanshu, Former Han History).

A number of Chinese envoys were then sent to Central Asia, triggering the development of the Silk Road from the end of the 2nd century BC.^[55]

Contacts with the Indian subcontinent (250–180 BC)

The Indian emperor Chandragupta, founder of the Mauryan dynasty, conquered the northwestern subcontinent upon the death of Alexander the Great around 323 BC. However, contacts were kept with his Greek neighbours in the Seleucid Empire, a dynastic alliance or the recognition of intermarriage between Greeks and Indians were established (described as an agreement on Epigamia in Ancient sources), and several Greeks, such as the historian Megasthenes, resided at the Mauryan court. Subsequently, each Mauryan emperor had a Greek ambassador at his court.

Kandahar Bilingual Rock Inscription of Ashoka (in Greek and Aramaic), found in Kandahar. c. 250 BC, Kabul Museum.

Chandragupta's grandson Ashoka converted to the Buddhist faith and became a great proselytizer in the line of the traditional Pali canon of Theravada Buddhism, directing his efforts towards the Indo-Iranic and the Hellenistic worlds from around 250 BC. According to the Edicts of Ashoka, set in stone, some of them written in Greek, he sent Buddhist emissaries to the Greek lands in Asia and as far as the Mediterranean. The edicts name each of the rulers of the Hellenistic world at the time.

The conquest by Dharma has been won here, on the borders, and even six hundred yojanas (4,000 miles) away, where the Greek king Antiochos rules, beyond there where the four kings named Ptolemy, Antigonos, Magas and Alexander rule, likewise in the south among the Cholas, the Pandyas, and as far as Tamraparni. (Edicts of Ashoka, 13th Rock Edict, S. Dhammika).

Some of the Greek populations that had remained in northwestern India apparently converted to Buddhism:

Here in the king's domain among the Greeks, the Kambojas, the Nabhakas, the Nabhapamkits, the Bhojas, the Pitinikas, the Andhras and the Palidas, everywhere people are following Beloved-of-the-Gods' instructions in Dharma. (Edicts of Ashoka, 13th Rock Edict, S. Dhammika).

Furthermore, according to Pali sources, some of Ashoka's emissaries were Greek Buddhist monks, indicating close religious exchanges between the two cultures:

When the thera (elder) Moggaliputta, the illuminator of the religion of the Conqueror (Ashoka), had brought the (third) council to an end ... he sent forth theras, one here and one there: ... and to Aparantaka (the "Western countries" corresponding to Gujarat and Sindh) he sent the Greek (Yona) named Dhammarakkhita ... and the thera Maharakkhita he sent into the country of the Yona. (Mahavamsa, XII).

Greco-Bactrians probably received these Buddhist emissaries (at least Maharakkhita, lit. "The Great Saved One", who was "sent to the country of the Yona") and somehow tolerated the Buddhist faith, although little proof remains. In the 2nd century AD, the Christian dogmatist Clement of Alexandria recognized the existence of Buddhist Sramanas among the Bactrians ("Bactrians" meaning "Oriental Greeks" in that period), and even their influence on Greek thought:

Thus philosophy, a thing of the highest utility, flourished in antiquity among the barbarians, shedding its light over the nations. And afterwards it came to Greece. First in its ranks were the prophets of the Egyptians; and the Chaldeans among the Assyrians;^[56] and the Druids among the Gauls; and the Sramanas among the Bactrians ("Σαρμαναίοι Βάκτρων"); and the philosophers of the Celts; and the Magi of the Persians, who foretold the Saviour's birth, and came into the land of Judea guided by a star. The Indian gymnosophists are also in the number, and the other barbarian philosophers. And of these there are two classes, some of them called Sramanas ("Σαρμάναι"), and others Brahmins ("Βραφμαναι").^[57]

Influence on Indian art during the 3rd century BC

Main article: Hellenistic influence on Indian art

One of the Hellenistic-inspired "flame palmettes" and lotus designs, which may have been transmitted through Ai-Khanoum. Rampurva bull capital, India, circa 250 BC.

The Greco-Bactrian city of Ai-Khanoum, being located at the doorstep of India, interacting with the Indian subcontinent, and having a rich Hellenistic culture, was in a unique position to influence Indian culture as well. It is considered that Ai-Khanoum may have been one of the primary actors in transmitting Western artistic influence to India, for example in the creation of the Pillars of Ashoka or the manufacture of the quasi-Ionic Pataliputra capital, all of which were posterior to the establishment of Ai-Khanoum.^[58]

The scope of adoption goes from designs such as the bead and reel pattern, the central flame palmette design and a variety of other moldings, to the lifelike rendering of animal sculpture and the design and function of the Ionic anta capital in the palace of Pataliputra.^[59]

First visual representations of Indian deities

Coin of Greco-Bactrian king Agathocles with Indian deities.

Indian coinage of Agathocles, with Buddhist lion and dancing woman holding lotus, possible Indian goddess Lakshmi.

One of the last Greco-Bactrian kings, Agathocles of Bactria (ruled 190–180 BC), issued remarkable Indian-standard square coins bearing the first known representations of Indian deities, which have been variously interpreted as Vishnu, Shiva, Vasudeva, Buddha or Balarama. Altogether, six such Indian-standard silver drachmas in the name of Agathocles were discovered at Ai-Khanoum in 1970.^[60][61][62] These coins seem to be the first known representations of Vedic deities on coins, and they display early Avatars of Vishnu: Balarama-Sankarshana with attributes consisting of the Gada mace and the plow, and Vasudeva-Krishna with the Vishnu attributes of the Shankha (a pear-shaped case or conch) and the Sudarshana Chakra wheel.^[61] Some other coins by Agathocles are also thought to represent the Buddhist lion and the Indian goddess Lakshmi, consort of Vishnu.^[62] The Indian coinage of Agathocles is few but spectacular. These coins at least demonstrate the readiness of Greek kings to represent deities of foreign origin. The dedication of a Greek envoy to the cult of Garuda at the Heliodorus pillar in Besnagar could also be indicative of some level of religious syncretism.

Diodotid dynasty

• Diodotus I Soter (255–235 BC) First King of Bactria, revolted against Seleucid Empire
• Antiochus I (disputed) son of Diodotus I, ruled Bactria c. 230s BC
• Diodotus II Theos (235–225 BC) son of Diodotus I

Euthydemid takeover (230–171 BC)

• Eucratides I the Great (170–c. 145 BC) Coins most important Greco-Bactrian king, likely a relative of Diodotus I
• Eucratides II (145–140 BC) Coins son of Eucratides I to whom he committed patricide
• Diodotus III Platon (c. 140–130 BC) co-ruler of Eucratides (also known by his birth name, Platon/Plato)
• Heliocles I (reigned c. 140–120 BC) last king of Bactria before its conquest by the Yuezhi

Euthydemid dynasty

Silver drachm of Menander I, dated circa 160–145 BC. Obverse: ΒΑΣΙΛΕΩΣ ΣΩΤΗΡΟΣ ΜΕΝΑΝΔΡΟΥ ('of King Menander the Saviour'), heroic bust of Menander, viewed from behind, head turned to left; Reverse: Athena standing right, brandishing thunderbolt and holding aegis, Karosthi legend around, monogram in field to left.^[63]

• Euthydemus I (reigned c. 225-200 BC)
• Demetrius I (r. c. 200–180 BC), invaded and conquered India, establishing the Indo Greek Kingdom.
• Euthydemus II (r. 180–171) last Euthydemid ruler of Bactria, killed alongside Demetrius by Eucratides.

Both Euthydemid and Diodotid rulers became kings of Arachosia and India, with the conquests of Demetrius and Eucratides, the Indo-Greek Kingdom was formed. Many of the dates, territories, and relationships between Greco-Bactrian kings are tentative, and essentially based on numismatic analysis and a few Classical sources. The following list of kings, dates and territories after the reign of Demetrius is derived from the latest and most extensive analysis on the subject, by Osmund Bopearachchi (Monnaies Gréco-Bactriennes et Indo-Grecques, Catalogue Raisonné, 1991)