As this remote corner of northeastern Syria fast slides out of government control, many Syrians are bracing for what they fear will be another war, between the relatively moderate fighters who first took up arms against the government and the Islamist extremists who emerged more recently with the muscle and firepower to drive the rebel advance.

The capture last month of the city of Raqqah, Syria's first provincial capital to fall under opposition control, consolidated the gains of an assortment of mostly Islamist-inclined groups across three northeastern provinces. Forces loyal to President Bashar Assad cling to just a tiny number of scattered bases and could be ejected anytime.

Yet even as the regime continues to hold out, schisms are emerging among rebel groups over ideology, the shape of a future Syrian state and control of the significant resources concentrated in this long-neglected but crucial corner of the country.