The Niger River is the principal river of western Africa, extending for over 2500 miles. It takes an unusual route, consisting of a boomerang shape, which baffled European geographers for two millennia. Its source is just 150 miles inland from the Atlantic Ocean, but the river runs eastward away from the sea into the Sahara Desert, spreading into a vast delta before it takes a sharp right turn and heads southeast to the Gulf of Guinea. The rich agricultural land fringing this delta has served as the 'bread-basket' for a succession of civilizations that date back to 250 B.C. Its ecological cycles of flood and drought encourage a complex web of human economies, from fishermen and rice agriculturists, to millet farmers and pastoralists who use the delta for grazing their cattle.