Sudan is a bastion of Arabism and Islam on the African continent. The scope of that study did not allow for the study of every branch, sub-tribe, clan, and lineage of each tribe. For example, the Ja'aliyyin tribe alone has over fifteen other main clans belonging to the Ja'aliyyin group that were not mentioned, and these fall under the name of the Abbasid tribes. In addition to many branches and sub-tribes of other tribes such as Juhaynah, Rabi'ah, Hilaliyyah, and the Ashraf al-Qurashiyyun. All these Arab tribes mixed with the local elements, and the degree of mixing was so strong and enjoyable that the Arabs took the tribes they associated with as allies and supporters against other tribes who were their enemies. From here, Arabism was strengthened by their cohesion with the inhabitants of Sudan in a way that indicates that the Arabs were able to carry the banner of Arabism and Islam in all these regions where they spread. The social environment contributed significantly to deepening the Arab migration to many parts of Sudan. Perhaps the change in the social environment through intermarriage is what benefited the Arab tribes and encouraged them to spread, reaching the southern regions where they mixed with the Shilluk, Dinka, Nuer, Nilotic tribes, and the inhabitants of the tropical forests. They also mixed with the inhabitants of the Nuba Mountains, where the social system had facilitated the rapid assimilation of Arab elements in Sudan and allowed the Arabs to control the political affairs of those lands. This political control and social superiority enabled them to work towards the spread of Islam and the spread of Arab-Islamic culture, to which Islam, its civilization, the Arabic language, and its various sciences contributed to the emergence of those Arab cultural features that all factors participated in to imbue Sudan with an Arab-Islamic character.