Looking at a map of religious demographics in the middle east and central Asia, we see that Sunni Islam is the dominant branch of Islam in these regions, with the exceptions of Iran and Iraq. Now looking at the map, you see the Middle East and North Africa dominated by Sunni Muslims, then you have the Shia in Iraq and Iran, and then you see the Sunni dominant in central Asia.
My knowledge of the History of Islam and its expansion is unfortunately lacking, but just looking at the map it doesn't make sense geographically that Sunni Islam is dominant in central Asia rather than Shia. So if someone could explain to me how that happened, it would be greatly appreciated.
So what I am wondering is how could we get Shia Islam to be dominant in Central Asia? What effects might this have on... well, history.