Let me guess who the Black Flags of Khorasan can be. There are three options, Iran, Afghanistan or Pakistan. Pakistan is not in the the traditional location called Khorasan, but we could imagine it is. In reality Pakistan is Hind, the land of Hindus, not known for bravery or war making ability.
There are four qualities needed to win wars. Faith, Brains, Technology and Bravery.
- Iranians have all four: Faith, brains, technology and bravery.
- Afghans have two: Faith and bravery, but no technology or brains.
- The British Indian Army of Pakistan led by whiskey drinking generals has none of these qualities.
So, I would say that the Black Flags of Khorasan will be Iranians, maybe aided by Afghans.