Ayutthaya began its hegemony by conquering northern kingdoms and city-states like Sukhothai,[4]:222 Kamphaeng Phet and Phitsanulok. Before the end of the fifteenth century, Ayutthaya launched attacks on Angkor, the classical great power of the region. Angkor's influence eventually faded from the Chao Phraya River Plain while Ayutthaya became a new great power.