What were the factors leading to the downfall of empires of:

Ghana-

Mali-

Songhai-

Ghana: Ghana was combined in the kingdom of Mali in 1240 marking the end of the Ghana Empire. A tradition in historiography maintains that Ghana fell when it was sacked by the Almoravid movement in 1076-77, although Ghanaians resisted attack for a decade. but this interpretation has been questioned. Mali: After Ghana fell because of invading forces and internal disputes, Mali rose to greatness under the leadership of a legendary king named Sundiata, the "Lion King." Later, another great leader named Mansa Musa extended the empire. After his death, however, his sons could not hold the empire together. Songhai: In 1590, al-Mansur took advantage of the recent civil strife in the empire and sent an army under the command of Judar Pasha to conquer the Songhai and to gain control of the Trans-Saharan trade routes. After the disastrous defeat at the Battle of Tondibi (1591), the Songhai Empire collapsed.