Rabi'ah and Qays 'Aylan as their collective leader. Al-Umari oversaw a huge gold mining enterprise in the region, and the industry financed his own virtual independence in Wadi Allaqi and Aswan. Although he twice defeated the Egyptian army of Ahmad ibn Tulun, the governor of Egypt (r. 868–884), and forced the latter to cease attempts to subjugate him, al-Umari assassinated by Mudhar tribesmen after suppressing a revolt by Rabi'ah. Following his fall, Arab tribal activity continued to increase in the Eastern Desert region. The Rabi'ah emerged as the strongest of the Arab tribes inhabiting the Egyptian-Nubian frontier region. By the 10th century, they were running a principality that replaced that of al-Umari's. The Rabi'ah was able to grow powerful because of their alliance with the indigenous Beja people, namely the Muslim Hadariba tribe, which controlled the region between the Red Sea coastline and the eastern banks of the Nile River. The alliance manifested in business partnerships in the mining industry and intermarriage, including between the chiefs of the two tribes. The sons of Rabi'ah father and Hadariba mothers inherited the lands and titles of their maternal grandparents since Beja inheritance prioritized descent from the mother. Thus, by 943, Ishaq ibn Bishr, who was born to a Rabi'ah father, became the chief of the Rabi'ah-Hadariba principality after succeeding his maternal Beja uncles Abdak and Kawk. According to the 14th-century Arab historian Ibn Fadlallah al-Umari, the Rab'iah and Beja "became like one" during Ishaq's reign. The latter was killed during an intra-tribal war in Wadi Allaqi, and was succeeded by a paternal cousin from Bilbays, Abu Yazid ibn Ishaq. Abu Yazid established Aswan as the principality's capital and was recognized by the Fatimid Caliphate, which controlled Upper Egypt, as the "protector of Aswan". Kanz al-Dawla and integration into the Fatimid state In 1006, Abu Yazid's son and successor, Abu al-Makarim Hibatallah, was given the title of Kanz al-Dawla (Treasure of the State) by Fatimid caliph Al-Hakim bi Amr Allah as an honorary reward for capturing the anti-Fatimid rebel Abu Rakwa. Thenceforth, Abu al-Makarim's successors inherited the Kanz al-Dawla title, while the mixed Rabi'ah-Hadariba people of their principality became known as the "Banu Kanz" (also spelled Banu'l Kanz, Banu al-Kanz or Kunuz). The principality of the Banu Kanz included the countryside of Aswan to the north, the frontier with Nubia to the south and most of the Eastern Desert between Aswan and the