Looking at this chapter in your text, there are very few leaders mentioned. The main point of this part of the chapter is that kingdoms such as Songhay and Kongo were built on trade and were greatly affected by the coming of the Europeans and their ships, which allowed for trade to be conducted by sea.
The kingdoms of Songhay and Kongo were based on trade. Songhay was based on the control of the overland trade between West Africa and the Mediterranean. Songhay was able to control this trade and make money off of it. Kongo was based largely on trade between the interior of Africa and the Portuguese. For both of these kingdoms, the major turning point was the coming of the Europeans.
The coming of the Europeans essentially doomed Songhay. The European ships were able to carry goods more efficiently than overland carriers could. This meant that the trade the Songhay depended on dried up. This led to the decline and fall of Songhay. By contrast, the coming of the Portuguese allowed Kongo to flourish at first. Kongo traded things like copper, ivory, and slaves for European goods. This allowed the kingdom to become rich and powerful. However, the kingdom also declined and fell because of the Portuguese. As the Portuguese found other areas with which to trade, Kongo lost its share of the trade and became weaker and poorer.
The two main leaders mentioned in the chapter are Sunni Ali, ruler of Songhay, and King Nzinga Mbemba of Kongo. Ali rtuled from 1464 to 1493. He made his kingdom more organized and efficient than it had been. Nzinga Mbemba ruled from 1506 to 1542. He was instrumental in forging close ties with the Portuguese, allowing Kongo to prosper.