 By the late 12th century Anawrahta's successors had extended their influence farther to the south into the upper Malay peninsula, to the east at least to the Salween river, in the farther north to below the current China border, and to the west, in northern Arakan and the Chin Hills.In the 12th and 13th centuries, Pagan, alongside the Khmer Empire, was one of two main empires in mainland Southeast Asia.The Burmese language and culture gradually became dominant in the upper Irrawaddy valley, eclipsing the Pyu, Mon and Pali norms by the late 12th century.