محمد بن جرير الطبري
Following their victory, the Khazars occupied Ardabil. The next year, however, Barjik led an army to Mosul and was defeated. According to Muhammad ibn Jarir al-Tabari and other Arab historians, the Muslims were so enraged by Barjik's desecration of their commander's head that they fought with extra vigor. After the defeat at Mosul, the Khazar army withdrew north of the Caucasus Mountains.