After the conquest of Egypt, the Muslims led disciplinary campaigns into the land of Nubia. The desire of Caliph Umar, may Allah be pleased with him, coincided with the desire of his commander in Egypt, Amr ibn al-As, for the necessity of invading Nubian lands to ensure the protection of Egypt's southern borders and to secure the ancient trade route between the two countries. This could only be achieved by silencing the aggressions of the Nubians. Arab sources agree that two main campaigns entered the land of Nubia. The first was during the governorship of Amr ibn al-As, by order of the Commander of the Faithful, as we have clarified before, and it was in the year 23 AH / 644 AD. The second was during the reign of Abdullah ibn Sa'd ibn Abi Sarh in the year 31 AH / 651 AD. The campaign led by Amr ibn al-As, under the command of Uqba ibn Nafi, did not succeed in stopping the Nubian harassments, which prompted Abdullah ibn Sa'd ibn Abi Sarh to direct the second Muslim campaign against the land of Nubia. Ibn Abi Sarh's army was able to penetrate south to Dongola, the capital of the northern Christian kingdom, and besieged it severely. They used catapults to strike the city, destroying their church, which prompted their king to make peace with the Muslims. A treaty was signed with them, known in history as "Al-Baqt." Among its most important provisions were that the warring parties would enter each other's lands without settling, and that the Nubians would maintain the mosque built by the Muslims in their city, not prevent any worshipper from it, and be responsible for its upkeep and lighting. They were also to pay 100 heads of their best slaves to the Muslim leader. This defeat was followed by an influx of Arab tribes to buy land from the Nubians in the region of Al-Mairis and settle there. They intermarried with the Nubians and mixed with them. To this group is attributed the credit for spreading Islam in those regions. The Banu al-Kinaz, a branch of Rabi'a, had the largest share in strengthening the Islamic influence in central Nubia, as they allowed them to marry and mix with them.