It was on the continent of Africa that the first hominids arose some three million years ago. Forty thousand years ago, Homo sapiens first appeared. It was in Africa, too, that crops were first cultivated and animals first domesticated. One of the earliest 'modern states' developed along the Nile, at Nubia and Egypt.  After the decline of Egypt, major developments in Africa took place in the Western portion of the continent, where a series of trading states controlled commerce. Along the east coast of Africa, other states also developed.