Final answer:
Usman dan Fodio was the leader who sparked an Islamic revival across West Africa in the early 1800s, and the Mali Empire was created by Sundiata Keita. Leo Africanus was a writer who provided insights into East African cultures.
Step-by-step explanation:
The leader who sparked an Islamic revival across West Africa in the early 1800s was Usman dan Fodio. He led a religious movement that resulted in the establishment of the Sokoto Caliphate, which greatly influenced the spread of Islam and the reform of Islamic practices in the region.
The empire of Mali was created by Sundiata Keita, also known as Sundiata Kieta. He is often regarded as a great king and the founder of the Mali Empire. His reign saw the expansion of trade, as well as the consolidation of Islamic faith in the empire.
Leo Africanus was a notable figure whose writings have provided a substantial amount of information about the cultures of East Africa. He was not, however, the founder of the Mali Empire.