The Mandailing is an ethnic group in Sumatera, Indonesia that is commonly associated with the Batak people. They are found mainly in the northern section of the island of Sumatra in Indonesia. They came under the influence of the Kaum Padri who ruled the Minangkabau of Tanah Datar. As a result, the Mandailing were influenced by Muslim culture and converted to Islam. There are also a group of Mandailing in Malaysia, especially in the states of Selangor and Perak. They are closely related to the Angkola.