After Leo assumed the imperial title, the land of his mountaineer allies was invaded by Umar II's forces. A Khazar chieftain, Barjik, hastened to their succor and, in 722, the joint Alan-Khazar army inflicted a defeat on the Arab general Tabit al-Nahrani. The Khazars erected Skhimar and several other strongholds in Alania at this period. In 728 Maslamah ibn Abd al-Malik, having penetrated the Gate of the Alans, devastated the country of the Alans. Eight years later, Marwan ibn Muhammad passed by the Gate in order to ravage the forts in Alania. In 758, as Ibn al-Faqih reports, the Gate was held by another Arab general, Yazid ibn Usayd.