 Peace reigned in the Caucasus between Arabs and Khazars until 799 , when the last major Khazar attack into Transcaucasia took place . Chroniclers again attribute this attack to a failed marriage alliance . According to Georgian sources , the khagan desired to marry the beautiful <unk> , daughter of Prince Archil of Kakheti ( r . 736 – 786 ) , and he sent his general <unk> to invade Iberia and capture her . Most of the central region of K 'art <unk> was occupied , and Prince <unk> ( r . 786 – 807 ) was taken off into captivity for a few years , but rather than be taken off captive , <unk> committed suicide and the furious khagan had <unk> executed . Arab chroniclers , on the other hand , attribute this to the plans of the Abbasid governor al @-@ Fadl ibn Yahya ( one of the famous Barmakids ) to marry one of the khagan 's daughters , who died on her journey south , while a different story is reported by al @-@ Tabari , whereby the Khazars were invited to attack by a local Arab magnate in retaliation against the execution of his father , the governor of Derbent , by the general Sa 'id ibn Salm . According to the Arab sources , the Khazars then raided as far as the Araxes , necessitating the dispatch of troops under Yazid ibn Mazyad , as the new governor of Transcaucasia , with more forces under <unk> ibn <unk> in reserve . 
