The empire of Songhai was originally part of Mali.
More about the empire of Songhai:
In the 15th and 16th centuries, the western Sahel/Sudan was ruled by the Songhai Empire, often written as Songhay. It was one of the biggest states in African history at its height. The state is known by its historical name, which was inspired by the Songhai, the state's dominant ethnic group and ruling class.
Despite the fact that a Songhai state had existed in and around Gao since the 11th century, Sonni Ali chose to make Gao the imperial capital.
The Songhai Empire, which included the present republics of Burkina Faso, Ivory Coast, Guinea, Gambia, Mali, Mauritania, Senegal, and Algeria (south), surpassed Mali as the most significant empire in West Africa. From the time of King Sonni Ali, the Songhai would drastically increase the size of their kingdom, which had initially only a small region along the eastern bank of the Nigher river.
Social Darwinism held that those made better or worse by industrialization were based on the natural predisposition of the people effected. For those who were made better off, the success of those people demonstrated that they had a well-evolved culture and this expansion would help remove or improve underperforming cultures, which were those "chosen" by the fact that they were performing poorly.
All in all, according to the Social Darwinist, Imperialism was the natural expansion and success of a well-evolved culture and this expansion would help remove or improve underperforming cultures. social darwinism was used to justify imperialism because social darwinism was the idea that the stronger race would survive and the weaker would die off. in many cases imperialism was justified by the thought that the country being taken over was weaker and needed help, thus the "greater country" could force its customs on the other country.