The only country in Southeast Asia never colonized, Thailand was known for centuries as Siam. Thailand’s government structure has undergone gradual and practical evolution in response to the changing environment. Ever since 1932, it has been a constitutional monarchy with a parliamentarian form of government. The bicameral parliament is composed of elected representatives and appointed senators. The Prime Minister is selected from among members of the House of Representatives. Appointed governors administer 75 of the country's 76 provinces. The Bangkok Metropolis Administration is administered by an elected governor and is divided into 38 districts. The country is divided into 76 provinces, each administered by an appointed governor, which are sub-divided into district, sub-districts, and villages.