How many years passed from Ghana's decline to the Mali Empire consolidating western Sudan?

Context: By the ninth century CE, a string of dynastic states, including the earliest Hausa states, stretched across the sub-Saharan savannah from the western regions to central Sudan. The most powerful of these states were Ghana, Gao, and the Kanem-Bornu Empire. Ghana declined in the eleventh century, but was succeeded by the Mali Empire which consolidated much of western Sudan in the thirteenth century. Kanem accepted Islam in the eleventh century.

Answer: Ghana declined in the 11th century, Mali Empire consolidated much of western Sudan in the 13th century, so 2 centuries passed which equals 200 years.