Malaysia is a federal constitutional elective monarchy, and the only federation in Southeast Asia. The system of government is closely modelled on that of the Westminster parliamentary system, a legacy of British colonial rule. The head of state is the Yang di-Pertuan Agong, commonly referred to as the King. The King is elected to a five-year term by and from among the nine hereditary rulers of the Malay states; the other four states, which have titular Governors, do not participate in the selection.