Question

How a sunni muslim dominated country like iran became shiiat country?

Answer 1

First of all

Bis milla hir rahmanir rahim

Nowadays Iran is one of the most powerful Shia country in the world.
But actually from the beginning it is a sunni dominated country. In the reign of safavid dynasty it becomes a Shia dominated country in the early 16th century

Hope it helps u

Assalamu alaikum