Something doesn’t make sense to me. The total number of people in ISIS wouldn’t fill half a football stadium , yet they control territory the size of NY and NJ combined.
Controlling territory isn’t totally about number of people, it’s about strategy and terrain....
If I took control of the southern Mississippi River with 10,000 soldiers and the equipment to do so...all the surrounding lands for hundreds of miles would be under my domain...
Of course having no opposition would be important factor like in northen Iraq ....