Andriana is both the name of the noble class and a title of nobility in Madagascar. Historically, many Malagasy ethnic groups lived in highly stratified caste-based social orders in which the andriana were the political and/or spiritual leaders. Among the Merina of the central highlands of Madagascar, the emergence of a noble class is attributed to its decree by King Andriamanelo (1540–1575), later subdivided into four sub-castes by King Ralambo (1575–1600) and eventually six sub-castes by King Andriamasinavalona (1675–1710).