As for the Beja, their raids on the southern borders of Egypt were not limited to the year 400 AH. They attacked again around the year 422 AH, and the commander Ibn al-Habhab made peace with them and concluded a treaty. However, they soon resumed their attacks on the Aswan region. Al-Ma'mun sent a campaign against them led by Ibn al-Jahm in the year 423 AH. Battles took place between them, which ended with a truce and a treaty with their leader, Kanun bin Abdul Aziz. Following Ibn al-Jahm's campaign, the Arabs discovered gold and emeralds in the land of minerals in Beja land. This led to a flow of Muslims seeking wealth towards the land. The success of some migrants led to more fortune-seekers following, which in turn contributed to the spread of Islam among the indigenous population after intermarriage and intermingling with the Arabs. These successive Islamic migrations to Sudan ultimately led its people to embrace Islam and the collapse of Christian Sudanese kingdoms under the increasing human tide of Muslim groups. The establishment of three Islamic African kingdoms, the Funj, Taqali, and Darfur, was also a result of these migrations. There were main reasons that prompted Muslims to move to eastern Sudan, the most important of which were: 1. Military campaigns launched from Egypt to northern and eastern Sudan. 2. The search for stability and livelihood. Umar, may God be pleased with him, did not allow warriors to own land in conquered countries, which pushed them to migrate south in search of sustenance. 3. Political pressures exerted by some caliphs towards the Arabs, such as Al-Mu'tasim and others. These pressures caused the Arabs to migrate south, fleeing the oppression and injustice of the rulers.