Your challenge is to create a Persia/Iran that has survived to modern days (whether Republic or Empire or whatnot) and is a minimum twice the current size of Iran
Would any part of Afghanistan be doable?
They tried for Herat IOTL. Britain told them "No".Would any part of Afghanistan be doable?
Anyone got a rough map handy?
I'm thinking 1800s POD
Western Afghanistan (and all of Tajikistan) would be doable, yes, especially since the two predominant languages in Afghanistan are Dari (the local name for the Persian language, Farsi) and Pashto (a separate Iranic language).
Possible idea: The Timurids don't get kicked out of Persia (lasting for far longer) but still expand into India. The next dynasty manages to smothly integrate those areas. Today's Iran still has them.