Furthermore, some Muslims from Aswan had purchased estates within Nubian lands. Thus, there was no longer a need to occupy and annex them to Islamic territories. In the third Hijri century, 333 AH / 846 CE, the Beja raided the city of Qift. However, the Abbasid Caliph Al-Ma'mun dispatched a campaign against them and concluded a treaty with them. This treaty stipulated that the lands between Aswan and Jum'a would be under the authority of a king appointed by the Caliph. The leader of the Beja, (Kanun bin Abdul Aziz) - and this name is evidence of the spread of Islam among the Beja - and his people were to be subjects of the Commander of the Faithful. From this, it is clear that Islam made its way into the land of the Beja, just as it did into the land of Nubia. This is evidenced by the presence of mosques and Muslims, and by Muslim workers entering the lands of the Beja to collect Zakat from those who converted to Islam. This is clear evidence of the widespread dissemination of Islam, whether they were Arabs who had settled there or Beja who embraced Islam as a result of their interaction with the Arabs.

The foundations of Arabism and Islam were strengthened in Nubia after the killing of Marwan bin Muhammad, the last of the Umayyad caliphs, in Bumayr in Upper Egypt. His sons, Abdullah and Ubayd Allah, along with four thousand of their followers, headed to Nubia with the intention of settling there. However, the King of Nubia asked them to leave. Consequently, a portion of them decided to return to the Arabian Peninsula, while others took another route to migrate south and east. From here, Islam began to flow into Sudan in large numbers. It also appears that a group of Muslim Arabs were the first to settle in those regions, where they built mosques. All these circumstances paved the way for Arabs to interact with the Nubians and the Beja, and were among the factors that helped Arabize these two regions. The marriage of Arabs to Nubians had an impact on the latter's Islamization.

Thus, the Arab Islamic settlement served as a catalyst for expansion southward into Central Sudan, also known as the Kingdom of Alwa. From here, Sudan became open to Islam and Arab-Islamic culture to penetrate the center.