Rock art depictions of cattle, camels, and people in the Sahara region of Chad offer evidence that humans and animals once occupied this area. At the time rock art was done—from the fifth to the second millennium B.C.—the area was an open savanna, which supported the animals represented in the rock art.
(Photograph shot on assignment for, but not published in, "Journey to the Heart of the Sahara," March 1999, National Geographic magazine)
