answers: migrations
context: 4,000 to 3,000 years ago in West/Central Africa (the area of modern-day Cameroon). They were supposedly spread across Central, Eastern and Southern Africa in the Bantu expansion, a rapid succession of migrations during the 1st millennium BC, in one wave moving across the Congo basin towards East Africa, in another moving south along the African coast and the Congo River system towards Angola. The geographical origin of the Bantu expansion is somewhat open to debate. Two main scenarios are proposed, an early expansion to Central Africa, and a single origin of the migration radiating from there, or an early separation </s> was killed, and most of the Ndwandwe abandoned their lands and migrated north establishing Zulu-like (named Ngoni after the ethno-linguistic name "Nguni") kingdoms in Zambia, Malawi, Mozambique and Tanzania. This was the final phase of the Mfecane, a catastrophic, bloody civil war and eventual migration of many different tribes in the area, initially (ca. 1802) caused by famine but ultimately as a result of escaping from the Zulus. The Ngoni groups caused their own havoc by using Zulu tactics in war. They established stronger political units in other countries and thus posed a threat to European colonisation, for example during </s> whole shows that their ethno-geographic center was located in a small village called Chiconono, in the northwestern Mozambican province of Niassa. The majority of Yao were mainly subsistence farmers, but some were also active as ivory and slave traders. They faced social and political decline with the arrival in today's Niassa Province of the Portuguese, who established the Niassa Company, and settled in the region founding cities and towns, destroying the indigenous independent farm and trade economy and changing it to a plantation economy controlled by themselves. The expanding Portuguese Empire had established trading posts, forts and ports in East
question: what were the main reasons the bantu speaking tribes left central africa