The polygamy has existed in all over the African continent thanks to the fact that it represents an aspect of their culture and religion. These types of marriages have been more present in the whole history of Africa like no other continent in the world. One of the reasons why this has happened is because the African societies have managed to see that children were a form of wealth and this way a family with more children was considered to be more powerful. Under these circumstances the polygamy in Africa was considered to be part of the way you could build an empire.
Only after the colonial era in Africa has appeared the polygamy has started to be perceived as a taboo, as this was one of the things imported along with the colonists that took over some regions of Africa. Some people are saying that there was also an economic reason why this has happened: there were many issues of property ownership that conflicted a lot with the European colonial interest.
At first the polygamy was very popular in the west part of Africa, but as the Islam has started to diffuse in this region, the prevalence of polygamy has started to continuously reduce due to the restrictions that appeared to the number of wives.
For example polygamy is very widespread across Kenya and right now one of the most prominent single individual that is popularizing this practice is Akuku Danger who as managed to become famous thanks to the fact that he is married with over 100 wives.
Even if people are thinking about the fact that South Africa is by far one of the most developed countries in the region, there are still many traditionalists out there that are constantly practicing polygamy. Even the president of South Africa: Jacob Zuma is declaring openly that he agrees with plural marriages and he is currently married to 3 wives. And at the same time he has 20 children with these and the two previous wives that he had in the past.
Another country where the polygamy is accepted is Sudan. Under these circumstances the Sudanese president: Omar Hassan al-Bashir has always sustained polygamy and he says that these multiple marriages are one of the options available for Sudan in order to increase its population.
Overall the polygamy in Africa is a very common practice that you are going to find all over Africa, but it tends to be more popular especially in the West African countries. This practice is very common among the animist and the Muslim communities. For example in Senegal there are almost 47% of the marriages where they feature more than one woman. In the Arab nations the percentages are even higher and there is also the Bedouin population that you can find in Israel, where around 30% of them are part of multiple marriages. And along with all that there are also the Mormon fundamentalists who also live in polygamous families.