For some time, groups of Fulbe had been dominant in parts of the delta, thereby creating a complex hierarchy dating back through several waves of conquest. However, due to internecine warfare, they were never able to organize a countervailing force against the Bamana Kingdom. In 1818, an Islamic cleric named Aamadu Hammadi Buubu united the Fulbe under the banner of Islam and fought a victorious battle against the Bamana and their allies. He subsequently established his rule in the Inland Delta and the adjacent dry lands east and west of the delta.