Complex sentence: The city of Koh Ker was passed by the important strategic route of the Khmer empire, This road came from Angkor and Beng Meales to Koh Ker and continued to Prasat Preah Vihear and then to Phimai (Thailand) and Wat Phu (Vietnam).
Split into simpler sentences: The city of Koh Ker was passed by the important strategic route of the Khmer empire. Coming from Angkor and Beng Meales to Koh Ker this road led to Prasat Preah Vihear and from there to Phimai (Thailand) and Wat Phu (Vietnam).