In 1821, Khartoum was established  north of the ancient city of Soba, by Ismail Pasha, the third son of Egypt's ruler, Muhammad Ali Pasha, who had just incorporated Sudan into his realm. Originally, Khartoum served as an outpost for the Egyptian Army, but the settlement quickly grew into a regional centre of trade. It also became a focal point for the slave trade. Later, it became the administrative center and official capital of Sudan.