Mehmed Ali first sought Sudanese conscripts to avoid pulling fellahin from agriculture

Evidence

The ground was now prepared for the introduction of the new tactics. Initially the Pasha did not think of conscripting the fellahin of Egypt mainly because that would have meant moving productive labor from the agricultural sector which was the main source of revenue. Instead, he had his eye on the Sudan to supply him with docile, obedient soldiers for his new army, and in the summer of 1820 the Pasha dispatched two expeditions to the Sudan, one under the command of his son, Ismail Pasha, and the other under Mehmed Bey Defterdar, his son-in-law. The two expeditions numbered ten thousand soldiers and were composed of Maghribi and Egyptian bedouins as well as a force of Turkish-speaking infantry and cavalry. — Khaled Fahmy, All the Pasha_s Men_ Mehmed Ali, his…, 437