Monarchy has thrived in five countries of Southeast Asia, blending traditions of kingship from the pre-colonial era with modern forms of constitutional rule. Brunei, Thailand, Malaysia, and Cambodia have monarchs as titular heads of state; Indonesia uniquely has forms of monarchy that thrive in a republican context at the regional level. These two traditions of monarchy, one archaic and the other modern, coexist uneasily—especially in times of stress, whether because of succession or political instability. Therefore, to understand the dynamics of political stability in Thailand and Malaysia, the role of monarchs cannot be ignored.
The end of the colonial era in Southeast Asia was marked by the adoption, for the most part, of modern forms of statehood modeled on the democracies of the departing colonial rulers. Thailand was never colonized, but its monarchy modernized in response to pressure for democratic reform and adopted forms of government that established limits on its power. The nine traditional rulers of the Malay states that constituted the core of the new federation of Malaysia were enshrined as keepers of Malay tradition and defenders of Islam as the federal division of powers evolved. One of their number serves as the Malaysian king or Yang di-Pertuan Agong on a revolving basis.