In 1400, Timur, the Turco-Mongol conqueror, besieged Damascus. The Mamluk sultan dispatched a deputation from Cairo, including Ibn Khaldun, who negotiated with him, but after their withdrawal Timur sacked the city on 17 March 1401. The Umayyad Mosque was burnt and men and women taken into slavery. A huge number of the city's artisans were taken to Timur's capital at Samarkand. These were the luckier citizens: many were slaughtered and their heads piled up in a field outside the north-east corner of the walls, where a city square still bears the name ''Burj al-Ru'us'' (between modern-day Al-Qassaa and Bab Tuma), originally "the tower of heads".