Stock Photo: The Kalan minaret. Built in 1121-22AD during the reign of the Kharakhanid ruler Arslan Khan Muhammed, the minaret collapsed destroying a large section of the mosque. It was rebuilt during Arslan Khan Muhammed's life-time. Almost 50 m tall it so impressed Genghis Khan, he ordered that it be spared when Bukhara was pillaged in 1220AD.