We don't have accurate statistics because in much of the Middle East it is not convenient to have them, for ruling regimes in particular.
But the estimates are that they are about 25 to 30 percent of the Muslim world, which puts them somewhere between 230 and 320 million people....
Pakistan is the second-largest Shia country in the world, with about 30 million population.
Also potentially, there are as many Shias in India as there are in Iraq.
Pakistan has the second-largest Sunni population in the world, while India has the second-largest Shia Muslim (Twelver) population.
Iran always had been a Shia country, the largest one, with a population of about 70 million.
Mutah is not the same as Misyar marriage or 'Arfi marriage, which has no date of expiration and is permitted by some Sunnis.
A Misyar marriage differs from a conventional Islamic marriage in that the man does not have financial responsibility of the woman by her own free will.
A dispute over succession to Muhammad as a caliph of the Islamic community spread across various parts of the world, which led to the Battle of Jamal and Battle of Siffin.
The dispute intensified greatly after the Battle of Karbala, in which Hussein ibn Ali and his household were killed by the ruling Umayyad Caliph Yazid I, and the outcry for revenge divided the early Islamic community.