The area now known as Malawi has seen massive tribe migrations for hundreds of years. Probably the most significant of which was that of the great Bantu tribes. Spread across Uganda, Kenya, Zambia and Mozambique, the Bantu tribe slowly swallowed up weaker tribes during their move from western Africa into the central and eastern parts of Africa. Malawi is host to several cave paintings (in Mangochi and the Nyika Plateau to name two) that date back to the Iron Age.
Somewhere between the 14th and 16th centuries, two main tribes moved into Malawi: the Tumbuka from the Congo moved into the northern region, while the Chewa from Zambia moved into the southern region. They have remained in these areas to this day. The Maravo Confederacy was established by Bantu people immigrating into the Shire River valley (emptying into Lake Nyassa) around 1480 A.D. It flourished into the 18th century, extending into stretches now belonging to Zambia and Mozambique. The Yao invaded southern Malawi in the 19th century, capturing weaker tribes for slave trade. It is believed that they were armed with firearms from Arab traders in the area.
The slave trade became a very big business in Malawi during this period. A heavy Arab influence in the area contributed to this. Of course, slave trading had existed throughout Africa for many centuries, but this era saw a new level of trade on an international scale. Malawi towns like Nkhotakota and Karonga served as major slave trade centers.