In c. 1449 in the north of what is now Niger, the Sultanate of Aïr was founded by Sultan Ilisawan, based in Agadez. Formerly a small trading post inhabited by a mixture of Hausa and Tuaregs, the sultanate grew rich due to its strategic position on the Trans-Saharan trade routes. In 1515 Aïr was conquered by Songhai, remaining a part of that empire until its collapse in 1591. The following centuries present a somewhat confused picture, though it seems that the sultanate entered a decline marked by internecine wars and clan conflicts. When Europeans began exploring the region in the 19th century much of Agadez lay in ruins, and it was taken over, though with difficulty, by the French (''see below'').