Between 2500–3000 years ago, Bantu-speaking peoples began a millennia-long series of migrations eastward from their homeland around southern Cameroon.
This Bantu expansion introduced agriculture into much of the African Great Lakes region.
During the following fifteen centuries, the Bantu slowly intensified farming and grazing over all suitable regions of East Africa, in the process making contact with Austronesian- and Arabic-speaking settlers on southern coastal areas.
The latter also spread Islam to the coastal belt, but most Bantu remained African Traditional Religion adherents.

Over a period of many centuries, most hunting-foraging peoples were displaced and absorbed by incoming Bantu communities, as well as by later Nilotic communities.
The Bantu expansion was a long series of physical migrations, a diffusion of language and knowledge out into and in from neighboring populations, and a creation of new societal groups involving inter-marriage among communities and small groups moving to communities and small groups moving to new areas.

After their movements from their original homeland in West Africa, Bantus also encountered in central east Africa peoples of Cushitic origin.
As cattle terminology in use amongst the few modern Bantu pastoralist groups suggests, the Bantu migrants would acquire cattle from their new Cushitic neighbors.
Linguistic evidence also indicates that Bantus most likely borrowed the custom of milking cattle directly from Cushitic peoples in the area.

On the coastal section of the African Great Lakes region, another mixed Bantu community developed through contact with Muslim Arab and Persian traders, leading to the development of the mixed Arab, Persian and African Swahili City States.
The Swahili culture that emerged from these exchanges evinces many Arab and Islamic influences not seen in traditional Bantu culture, as do the many Afro-Arab members of the Bantu Swahili people.
With its original speech community centered on the coastal parts of Tanzania (particularly Zanzibar) and Kenya—a seaboard referred to as the Swahili Coast—the Bantu Swahili language contains many Arabic loan-words as a consequence of these interactions.

The earliest Bantu inhabitants of the east coast of Kenya and Tanzania encountered by these later Arab and Persian settlers have been variously identified with the trading settlements of Rhapta, Azania and Menouthias referenced in early Greek and Chinese writings from AD 50 to AD 500, ultimately giving rise to the name for Tanzania.
These early writings perhaps document the first wave of Bantu settlers to reach central east Africa during their migration.

Between the 14th and 15th centuries, large African Great Lakes kingdoms and states emerged, such as the Buganda and Karagwe kingdoms of Uganda and Tanzania.
Between 2500–3000 years ago, Bantu-speaking peoples began a millennia-long series of migrations eastward from their homeland around southern Cameroon. This Bantu expansion introduced agriculture into much of the African Great Lakes region. During the following fifteen centuries, the Bantu slowly intensified farming and grazing over all suitable regions of East Africa, in the process making contact with Austronesian- and Arabic-speaking settlers on southern coastal areas. The latter also spread Islam to the coastal belt, but most Bantu remained African Traditional Religion adherents.
Over a period of many centuries, most hunting-foraging peoples were displaced and absorbed by incoming Bantu communities, as well as by later Nilotic communities. The Bantu expansion was a long series of physical migrations, a diffusion of language and knowledge out into and in from neighboring populations, and a creation of new societal groups involving inter-marriage among communities and small groups moving to communities and small groups moving to new areas.
After their movements from their original homeland in West Africa, Bantus also encountered in central east Africa peoples of Cushitic origin. As cattle terminology in use amongst the few modern Bantu pastoralist groups suggests, the Bantu migrants would acquire cattle from their new Cushitic neighbors. Linguistic evidence also indicates that Bantus most likely borrowed the custom of milking cattle directly from Cushitic peoples in the area.
On the coastal section of the African Great Lakes region, another mixed Bantu community developed through contact with Muslim Arab and Persian traders, leading to the development of the mixed Arab, Persian and African Swahili City States. The Swahili culture that emerged from these exchanges evinces many Arab and Islamic influences not seen in traditional Bantu culture, as do the many Afro-Arab members of the Bantu Swahili people. With its original speech community centered on the coastal parts of Tanzania (particularly Zanzibar) and Kenya—a seaboard referred to as the Swahili Coast—the Bantu Swahili language contains many Arabic loan-words as a consequence of these interactions.
The earliest Bantu inhabitants of the east coast of Kenya and Tanzania encountered by these later Arab and Persian settlers have been variously identified with the trading settlements of Rhapta, Azania and Menouthias referenced in early Greek and Chinese writings from AD 50 to AD 500, ultimately giving rise to the name for Tanzania. These early writings perhaps document the first wave of Bantu settlers to reach central east Africa during their migration.
Between the 14th and 15th centuries, large African Great Lakes kingdoms and states emerged, such as the Buganda and Karagwe kingdoms of Uganda and Tanzania.
East Africa