Final answer:
Sosso King Sumanguru started his rule around 1200, during a period of change in West Africa following the decline of the Ghana Empire.
Step-by-step explanation:
Sosso King Sumanguru began his reign around the year 1200.
The Sosso Kingdom emerged as a powerful state in West Africa after the decline of the Ghana Empire and the collapse of the Islamic Almoravid state. This transition period saw the rise of new goldfields and trade routes that allowed different groups, including the southern Soninke and Malinke peoples, to assert their dominance. The Sosso, under the leadership of King Sumanguru, capitalized on these changes and established their kingdom.
Although notorious for its acts of violence and raiding neighboring kingdoms, the Sosso Kingdom was ultimately vanquished by Sundiata Keita in 1235, leading to the founding of the Mali Empire.