As a diverse country consisting of people from various religions and ethnic backgrounds cemented by the Persian culture, Iran is the most populous country in the Persian Gulf region and is one of the largest economies in the Middle East. It is one of the richest and oldest cultures in the world. For over three thousand years, it was a melting pot of civilizations and demographic movements between Asia and Europe. Iran became an Islamic Republic in 1979; and thereafter its institutional system has comprised a popularly elected President and Parliament (the Majlis). With the world's second biggest proven oil and gas reserves and considerable mining resources, a dynamic and entrepreneurial middle class, and a well-educated labour force, Iran's economic potential is considerable. Iran is in transition to a market economy.