to colonize the entire Old World, and perhaps later on giving rise to Homo floresiensis. Although some recent writers suggest that H. georgicus, a H. habilis descendant, was the first and most primitive hominid to ever live outside Africa, many scientists consider H. georgicus to be an early and primitive member of the H. erectus species. The fossil and genetic evidence shows Homo sapiens developed in Southern and East Africa by around 350,000 to 260,000 years ago. and gradually migrated across the continent in waves. Between 50,000 and 60,000 years ago, their expansion out of Africa launched the colonization of the planet by modern humans. By 10,000 BCE, Homo sapiens had spread to all corners of the world. This dispersal of the human species is suggested by linguistic, cultural and genetic evidence. During the 11th millennium BP, pottery was independently invented in West Africa, with the earliest pottery there dating to about 9,400 BC from central Mali. It spread throughout the Sahel and southern Sahara. After the Sahara became a desert, it did not present a totally impenetrable barrier for travelers between north and south because of the application of animal husbandry towards carrying water, food, and supplies across the desert. Prior to the introduction of the camel, the use of oxen, mule, and horses for desert crossing was common, and trade routes followed chains of oases that were strung across the desert. The trans-saharan trade was in full motion by 500 BCE with Carthage being a major economic force for its establishment. It is thought that the camel was first brought to Egypt after the Persian Empire conquered Egypt in 525 BCE, although large herds did not become common enough in North Africa for camels to be the pack animal of choice for the trans-saharan trade. West Africa The Bantu expansion is a major migration movement that originated in West Central Africa (possibly around Cameroon) around 2500 BCE, reaching East and Central Africa by 1000 BCE and Southern Africa by the early centuries CE. The Djenné-Djenno city-state flourished from 250 BCE to 900 CE and was influential to the development of the Ghana Empire. The Nok culture of Nigeria (lasting from 1,500 BCE to 200 CE) is known from a type of terracotta figure. There were a number of medieval empires of the southern Sahara and the Sahel, based on trans-Saharan trade, including the Ghana Empire and the Mali