It is thought that the early bantu migrations circa 1000 bce through africa were caused by

Bantu is loosely translated as "people," which refers to a group of about 500 different African languages in Africa. Most of the first Bantu speakers have lived in the area in the west side of Africa, known today as Nigeria and Cameroon. Their migrations were mostly caused by agriculture and iron-working.

Since the innovation of agriculture had started to cultivate in the Bantu speakers, their search for land to plant yams and oil bearing palms was reason enough for them to migrate into different parts of Africa. Crops became a part of their daily life as well as herding domestic goats. They needed an area where they can expand this practice and to accommodate their growing population.

Another reason is iron. When iron started to be worked on, they crafted tools that facilitated ease in their "slash-and-burn" type of agriculture. Iron was also made into good weapons that were used as trade items that pushed the Bantu speakers to occupy other lands that are interested in their craft.