And then the widespread and numerous expansion of Arab and Sabaean tribes helped their migration south to the Gezira region. With the fall of the Umayyad state, the state of the Arabs ended, and the Abbasid state was established with the support of the Mawali (clients) from the Persians and some Arabs. The Abbasid state relied on Khurasani soldiers, who were a branch of the Persians and Arabs, and thus its reliance on Arabs decreased. Consequently, the Arabs were deprived of many of their privileges and wealth. They gradually lost their positions, and then, during the reign of Caliph Al-Mu'tasim, Turkish soldiers occupied their places. This did not please the Arabs, and a wide migration movement began to the peripheries of the Islamic state, where Arabs moved in large numbers towards the south, to the land of the Beja and Nubia, and to central Sudan. The decision of the Abbasid Caliph Al-Mu'tasim to write to his governor in Egypt, ordering him to dismiss Arabs from the Egyptian diwan and cut off their stipends, was carried out. This decision is considered a serious turning point in the history of Arabs in Egypt and the history of their migration to the south, which Arabized those regions. Hence, Al-Mu'tasim's decision to recruit Turks was the direct cause, indeed the primary factor, that encouraged the wide Arab migration to Sudan. This is because the more the Turks dominated the government and the army in Egypt, the more the Arabs were forced to migrate south towards Sudan. This policy even led some of them to migrate south into the desert, where they settled with their kinsmen and brothers who had settled there long before Islam. The harsh and severe methods shown by the Turkish governors towards the Arab tribes, the imprisonment of leaders, and the imposition of fines were fundamental reasons that pushed large numbers to spread south and west, away from this environment hostile to Arabism. How could it be otherwise, when they are the sons of the desert, accustomed to moving and traveling to distant horizons, followed by some of their family and clan who had settled there long before Islam?