Cambodia, officially the Kingdom of Cambodia, is a country in Southeast Asia on the Indochinese Peninsula. It spans an area of 181,035 square kilometres (69,898 square miles),  dominated by a low-lying plain and the confluence of the Mekong river and Tonlé Sap, Southeast Asia’s largest lake. It is dominated by a tropical climate and is rich in biodiversity. Cambodia has a population of about 17 million people, the majority of which are ethnically Khmer. Its capital and most populous city is Phnom Penh, followed by Siem Reap and Battambang.