Introduction

The great north-south rivers of Mainland Southeast Asia – the Mekong, Irrawaddy, Chao Phraya and Song Koi – along with their associated oodplains and deltas, are vital geographical features of this vibrant region of Asia. These waterways have historically provided modes of transport and commercial corridors to the coastal ports, passing through extensive forest tracts that for millennia have provided plentiful sources of architectural timber to the region’s great builder civilizations. The mountains that frame the river valleys provide a variety of stone sources that have contributed to the renowned carving and dry stone construction traditions evidenced at Angkor and Wat Phou. A cycle of dry and wet seasons in the region has made the development of sophisticated water management strategies an essential component of its successful civilizations. From the baray (reservoirs) and irrigation systems of ancient Khmer cities, to the harvesting of the Tonlé Sap sheries, and the extensive rice cultivation by the kings of Burmese and Champa civilizations, the people of Mainland Southeast Asia have long been adept at controlling their resource-rich environment.1