The vast majority of Iranians are Shia Muslims (90-95%), but in the larger Persian world the Shia-Sunni mix varies, with some countries being almost entirely Sunni.
The flavor of Islam in each region varies, with Iran’s Shia fundamentalism being among the most militant and restrictive. The regime in control of Iran is a theocratic dictatorship, in which the religious elite try to control the political, social and, economic lives of their people.
In the former Soviet parts of the Persian world, peoples who were Muslim before the Soviet era again view themselves as Muslims, even though they are often completely non-practicing.
The two things that set the Persian World apart from other Muslim regions are the strong presence of Shia Muslims (in Iran and Azerbaijan) and, in the former Soviet states, the varied opinions that people have about what it means to be Muslim, in societies where secular and Islamic values are in conflict.