They made their first appearance in various
parts of the region during the 7th and 8th centuries and reached their peak in the
late 9th and early 10th, a time when one subdivision of the region-central] avatemporarily
managed to outproduce the whole of the Southeast Asian mainland in terms of durable art and architecture. Such achievements point unmistakably to a substantial population, a developed regional economy, and a high level of social
control exercised by a cosmopolitan ruling class. They would also seem to point to
the existence of cities. Y ct, despite the splendor of the art and the profusion of the
monuments, identifiable urban places are in short supply.