Iran is a country located in Western Asia. It has a population of 77,176,930 people as of 2013, with a huge majority of citizens practicing the Shia Islam religion. Tehran is its capital city and Persian is its official language. The nation is recognized for having the world's oldest civilizations. Show more... It is governed by a unitary presidential Islamic republic political system. The country has the largest natural gas reserves in the world and is among the world's largest publishers of books.