The Treaty of Turkmenchay was an agreement between Qajar Iran and the Russian Empire, which concluded the Russo-Persian War (1826–1828). It was second of the series of treaties signed between Qajar Iran and Imperial Russia that forced Persia to cede or recognize Russian influence over the territories that formerly were part of Iran.

Tehran is the capital and largest city of Iran and also the largest city in Tehran Province. It also serves as the capital of the province, county and the Central District. With a population of around 9 million and 400 thousand in the city and around 16 million and 800 thousand in the larger metropolitan area of Greater Tehran, The Greater Tehran metropolitan area contains towns like the "New Town of Andisheh", "Islam Shahr", "Shahreh Qods", "Shahryar", "Pakdasht", "Firooz Kooh" and "Shamiran". Tehran is the most populous city in Iran and Western Asia, and has the second-largest metropolitan area in the Middle East, after Cairo. It is ranked 24th in the world by metropolitan area population.