Some Iranians were living in nowadays Georgia, Armenia &… and some of them fled from Muslim Invasion to India & Bangladesh &…

So from Georgia to Bangladesh, Nepal & India, They were all lots of Iranians there, so they survived till Arabs Kingdom finished, then, The culture came back to the country from where they survived, But for Syria & Egypt there were too close to Muslim Empire, so they had to just join.

Nowadays you can see old ancient Persian Culture in places from Georgia, Ossetia, Armenia & Azerbaijan to Pakistan, India & Bangladesh.