customary law of the indigenous peoples of Malaysia and Indonesia. It was the unwritten, traditional code governing all aspects of personal conduct from birth to death. Two kinds of Malay adat law developed prior to the 15th century: Adat Perpateh developed in a matrilineal kinship structure in areas occupied by the Minangkabau people in Sumatra and Negeri Sembilan; Adat Temenggong originated in bilaterally based territorial social units. Both adat forms were markedly transformed by Islamic and later European legal systems.
Learn more about adat with a free trial on Britannica.com.