The tribes of Tamim and Bali, and the use of that port helped spread Islam in northern Sudan and facilitate movement in those Sudanese regions. The Nubian groups that converted to Islam were influenced by Arab traditions, although they retained some of their old traditions and added some new influences. As time passed and their Islam strengthened, they completely abandoned their old traditions, adopting purely Islamic traditions. The tide of Arab migration intensified on a wide and rapid scale during the Fatimid era, due to the good relations between Cairo and Nubia. The reign of the Fatimid Caliph Al-Mustansir Billah, in particular, witnessed this mutual and ancient animosity between the Egyptian government and the clans and tribes in Nubia, driven by the success achieved by the migrating Arab-Nubian tribes in Upper Egypt. This led to the impetus of some of the early migrants and their motivation by news of the success and stability achieved by their brethren in the past, and their departure away from the oppression and tyranny of the Egyptian authorities, which was a driving force for the intensification of migration to Nubia, and their influence became clearer and stronger. Ibn Salim al-Aswani, who visited Nubia in 358 AH/969 AD, mentioned that the region extending from Aswan to the Third Cataract was managed by Muslims, not just by the Arab refugee migrants, but they managed it as owners and landowners, especially since they had bought some estates and lands a long time ago. Furthermore, the political instability in some periods of the Fatimid era between Egypt and Nubia did not hinder these migrations, because these migrations were not affected by political differences, as they were tribal migrations and population movements. More than that, Ibn Salim al-Aswani saw Muslims enjoying their full independence in this region, having integrated into the lives of the people, learned their language, and understood their customs and traditions. This is indicated by what Ibn Salim al-Aswani mentioned, that during his presence in Nubia, sent by the commander Jawhar al-Siqilli, his presence coincided with the festival