By the mid-1050s, Anawrahta's reforms had turned Pagan into a regional power, and he looked to expand. Over the next ten years, he founded the Pagan Empire, the Irrawaddy valley at the core, surrounded by tributary states. Anawrahta began his campaigns in the nearer Shan Hills, and extended conquests to Lower Burma down to the Tenasserim coast to Phuket and North Arakan. Estimates of the extent of his empire vary greatly. The Burmese and Siamese chronicles report an empire which covered the present-day Burma and northern Thailand. The Siamese chronicles assert that Anawrahta conquered the entire Menam valley, and received tribute from the Khmer king. One Siamese chronicle states that Anawrahta's armies invaded the Khmer kingdom and sacked the city of Angkor, and another one goes so far as to say that Anawrahta even visited Java to receive his tribute.