About 1045 two Arab tribes, the Beni-Hilal and the Beni-Soleim (originally from Central Arabia, and deported thence to Upper Egypt), left the right bank of the Nile to invade Barbary. They had made themselves troublesome in Upper Egypt; and the weakened rulers of that country, to get rid of them, had urged them to invade north-western Africa. About two or three hundred thousand crossed the desert and reached the frontiers of Tunis and Tripoli. They defeated the Berbers at the battle of Haiderān, and then settled in southern Tunis and western Tripoli. During their raids they destroyed the city of Kairwan, which never regained its former importance. Eventually some portion of them was unseated by the Berbers and driven westward into Morocco. They were succeeded by fresh drafts from Egypt and Arabia, but many of these later invaders settled in Barka and eastern Tripoli[36]. Later on other Arab tribes left the west coast of Arabia, and settled on the central Nile, avoiding the Abyssinian highlands, where they were kept at bay by their Christianized relatives of far earlier immigrations; and on the Blue Nile (Sennār), where they founded the powerful Funj empire which lasted from the 14th to the early 19th century. From the upper Nile they directed many and repeated invasions of Central and Western Africa. To this day tribes of more or less pure Arab descent are found in the districts round Lake Chad, in Darfur, Wadai, and in the western Sahara north of the Senegal and Niger rivers.