But one big difference soon became obvious: The fighters were suddenly flush with cash. Rumors circulated that they were paying a signing bonus of $400 to $500, a persuasive offer in a country where a lack of job prospects has helped fuel a new wave of youth emigration.
In a series of quick strikes, the Islamic State fighters began driving out local Taliban units, and officials say the splinter group now has a clear foothold across several districts in eastern Nangarhar Province, in rugged terrain on the border with Pakistan that had long been mostly out of government control.
The fighters may mostly be former Taliban, but they appear to have wholeheartedly taken up the calculated cruelty that the Islamic State has become known for, consolidating their hold with a brutality that has been shocking even by the standards of the Afghan insurgency.
Residents say that as soon as the jihadists would take a village they immediately began rounding up anyone even glancingly associated with either the government or the Taliban, including tribal elders. Many were summarily executed, including one group that was massacred en masse in a bomb detonation captured on video.