Complex sentence: Historically, many Malagasy ethnic groups lived in highly stratified caste-based social orders in which the "andriana" were the highest strata, above the Hova (Madagascar) (free commoner castes) and Andevo (slaves).
Split into simpler sentences: Historically, many Malagasy ethnic groups lived in highly stratified caste-based social orders in which the "andriana" were the highest strata. They were above the Hova (Madagascar) (free commoner castes) and Andevo (slaves).