The Kingdom of Thailand is located in Southeast Asia and its land area is roughly the size of France. The country shares borders with Myanmar (Burma), Laos, Cambodia, and Malaysia. Formerly called the Kingdom of Siam, it was renamed Thailand in 1939. Thailand is a constitutional monarchy with a parliamentary form of government. The king is Head of State. The Thai king, who has been on the throne since 1946, is currently the longest-serving Head of State in the world and the longest reigning monarch in the history of Thailand.