South Africa was the peak of colonization and slavery. By the late 1652 the Dutch had colonized majority of the cape colony. By 1854 the British and the Dutch had vast majority of land, hence, they started fighting. Then years later came in John Cecil Rhodes with the BSACO. This was the British Southern African Company, his motive was to expand trade and infrastructure. Inturn he started colonizing the whole southern region of Africa. From South Africa down to Zambia. Build a rail road across the nations and hence slavery came in. And also majority of the southern African people are called Bantu people who migrated from South Africa to the neighboring countries to seek refuge. That's why by now Southern Africa has a similar dialect .