Complex sentence: Ayutthaya established a presence at Nakhon Ratchasima and Phimai, however the bulk of the Khorat Plateau fell into the mandala of Lan Xang.
Split into simpler sentences: Ayutthaya established a presence at Nakhon Ratchasima and Phimai. However, the bulk of the Khorat Plateau fell into the mandala of Lan Xang.