Shiraz is the fifth-most-populous city of Iran and the capital of Fars Province, which has been historically known as Pars and Persis. As of the 2016 national census, the population of the city was 1,565,572 people, and its built-up area with Sadra was home to almost 1,800,000 inhabitants. A census in 2021 showed an increase in the city's population to 1,995,500 people. Shiraz is located in southwestern Iran on the rudkhaneye khoshk seasonal river. Founded in the early Islamic period, the city has a moderate climate and has been a regional trade center for over a thousand years.