Answer:
The Ghana Empire really began to collapse in the 12th century CE. The decline set in when other competing trade routes opened up further east and when the climate became unusually dry for a prolonged period, which affected agricultural production. The rulers of Ghana did not help themselves either as the empire was beset by a string of civil wars, the divisions perhaps based on the inherent conflict between Muslim and animist beliefs. Meanwhile, many rebellious chiefs took the opportunity of a weak central government to declare themselves independent of the empire, notably Tekrur in the Western Sudan region which controlled the Senegal River and which had even allied itself with the Almoravids.