It is therefore certain that soldiers originating from the edges of the Maghreb and bilād al-Sūdān were involved in the European venture. Often used by Arab geographers, this generic name does not allow their exact identity to be specified. Either way, it is highly probable that the army of Tāriq ibn Ziyād included Nubian and Beja soldiers, Blemmyes and people from Kānem, Bornū and Kawar, to which must be added hostages and slaves taken from the Kutāma, Zenāta, Hawāra, Ṣanhāja and Masmūda Berber tribes (Ibn 'Idhārī, 1983, vol. I, pp. 41-3). It is also known that after the Egyptian conquest, the Nubians were subject to violent attacks between the years $21 \mathrm{AH} / 641-2 \mathrm{CE}$ and $31 \mathrm{AH} / 651-2 \mathrm{CE}$. Troubled by the Nubians' fierce resistance, Abd Allah ibn Sa'd ibn Abī Sarḥ, Vice-Governor of Egypt and foster brother of the Caliph 'Uthmān (r. $23 \mathrm{AH} / 644 \mathrm{CE}-35 \mathrm{AH} / 656 \mathrm{CE}$ ), decided to offer them a peace treaty. However, one of the clauses in this pact, known under the Hellenistic Arabized form of bakṭ (Balādhurī, 1983, pp. 225, 238; Ibn Abī Dīnār, 1993, p. 42), demanded the annual delivery of three hundred and sixty slaves from the Nubians (Balādhurī, op. cit., p. 238). The historians 'Abd al-Hakam and al-Balādhurī also point out that the same obligation was imposed on the Berbers of Cyrenaica who were forced to pay the sum of 13,000 dinars as proof of their abdication (Balādhurī, op. cit., p. 225; Ibn 'Abd al-Hakam, op. cit., pp. 116-7). This demand was quickly commuted to human specimens (Ibn 'Abd al-Hakam, op. cit., p. 132). For their part, the Tubū (Chad), Hausa (Northern Nigeria) and Zaghāwa peoples (inhabiting the region between Lake Chad and the Bahr al-Ghazal) were subjected to the same ignominy following the attacks by 'Ukba ibn Nāfi in $46 \mathrm{AH} / 666$ CE beyond the oases of Zawīla and Fezzan (Balādhurī, op. cit., p. 226; Ibn 'Abd al-Hakam, op. cit., p.132; Ibn Abī Dīnār, op. cit., p. 42).