In December 1260, captaining a force of 8,000 rebels, Sargis engaged some 20,000 troops led by the Mongol general Arghun Aqa in the environs of Tashiskari and Akhaldaba.

Sargis fell back to the rebel king David's headquarters in Atsquri, but he succeeded in beating off Arghun's attack on his patrimonial fortress of Tsikhisjvari in May 1261.

He is reported to have pleaded himself guilty of a revolt in order to save his royal suzerain from Hulagu Khan's rage, citing corruption of the Il-Khan tax officials as a pretext.

The khan decided to reward Sargis's service by granting him the city of Karin, an honor blocked by jealous Georgian rivals who were able to convince the malleable king David of Jaqeli's treachery.

Having felt betrayed, Sargis broke with the Georgian court, but remained a faithful vassal to the Il-Khans and obtained from Hulagu the status of injü, that is, "crown land" in 1266.