Siem Reap is the 10th largest province in Cambodia. With a population of 896,309, it ranks as the 6th largest in the nation. A large portion of Siem Reap's southern border is demarcated by the Tonle Sap and as such, it is one of the nine provinces that making up the Tonle Sap Biosphere Reserve. In modern times the province is best known as the site of Angkor and the Angkor Wat temple ruins.