From archaeological evidence we know that the Bantu emerged around 3,000 BCE in West Africa and spread east and south, bringing with them the ancient cultural and linguistic antecedent of most of Africa below the Sahel.
The Bantu are a compilation of several hundred African ethnic groups that extend as far north as the Sahel and as far south as South Africa. In western linguistics, they are considered the 350-400 million speakers of the Bantoid branch of the of the Niger-Congo phylum of speakers. The Niger-Congo phylum consists of about 700-800 million speakers, meaning the Bantu language family comprise half or more of Niger-Congo (Niger-Congo itself comprises of roughly 60-70 percent of the entire African population).
The term Bantu is an attempt by linguist Wilhelm Bleek at the reconstruction of the proto-language deriving for the various forms in which the Bantu referred to themselves as "people". Versions of the word Bantu occur in all Bantu languages: watu in Swahili; bantu in Kikongo; anthu in Chichewa; batu in Lingala; bato in Kiluba; bato in Duala; abanto in Gusii; andũ in Kamba and Kikuyu; abantu in Kirundi, Zulu, Xhosa, Runyakitara.
Archaeological evidence suggests that the early Bantu began on the highland borders of Cameroon and Nigeria as far back in antiquity as 3,000 BCE (coinciding with pre-Dynastic Kemet, long before the building of the pyramids in modern day Egypt). From there theorists believe that around 1,500-1,000 BCE they spread through a mix of periods of mass migration and cultural diffusion throughout the continent to the regions of the far east, consisting of the Swahili coast, to as far south as the southern most point of modern-day South Africa (absorbing and transforming the now relatively small Khoisan languages).
Near the south-east border of modern Nigeria, specifically in Opi and Lejja, there is evidence of iron-smelting dating back to as early as 2,000 BCE. By at least 500 BCE the Bantu had taken up and spread the science of metallurgy (iron-smelting) throughout eastern (as represented by the Urewe culture) and eventually southern Africa. They also brought with them their creativity in creating art, iron tools, sculpture, and ceramics. The pre-Maafa (pre-colonial) Bantu populations were largely agricultural, but took up cattle herding as they mixed with Cushitic populations in the east.
By virtue of the extent of expansion, many of the great civilizations of Africa south of the Sahel are of Bantu heritage. This includes the aforementioned Swahili peoples of the east African coasts; the Shona whose ancestors built Mapungubwe, Great Zimbabwe and Mutapa; the Kongo Kingdom; Nzinga's Ndongo and Matamba Kingdoms; and the Zulu people whose great historical leader is known as Shaka. Many other modern groups and past civilizations are of Bantu heritage. This includes African people who suffered forced migration by way of Arabic or European slave traders. The Siddi of India are African Bantu peoples traded there by Arab and later Portuguese enslavers. This goes the same for the descendants of the enslaved African Dutch, African British, African French, African American, as well as the Caribbean and South-American African heritage populations of Jamaica, Haiti, Guyana, Trinidad, Virgin Island, St. Lucia, Belize, Brazil, Cuba, Venezuela, Mexico, and a host of other countries in the western world where enslaved Africans were displaced.