Roman as well as Persian, Indian, and Greek artifacts. By the 5th century, the state exercised control over the lower Mekong and the lands around the Tonle Sap. It commanded tribute from smaller states in the area now comprising northern Cambodia, southern Laos, southern Thailand, and the northern portion of the Malay Peninsula. Indianization was fostered by increasing contact with the subcontinent through the travels of merchants, diplomats, and learned Brahmins. Beginning in the early 6th century, civil wars and dynastic strife undermined Funan's stability. Funan disappears from history in the 7th century. The successor state, Chenla, is first mentioned in the Chinese Sui History as a Funan vassal. In the 8th century factional disputes at the Chenla court resulted in the splitting of the kingdom into rival northern and southern halves known as Land (or Upper) Chenla and Water (or Lower) Chenla. Land Chenla maintained a relatively stable existence, but Water Chenla underwent a period of constant turbulence, partly because of attacks from the sea by the Javanese and others. The Angkorian period or Khmer Empire lasted from the early 9th century to the early 15th century and was the golden age of Khmer civilization. Indravarman I (877–889) extended Khmer control as far west as the Korat Plateau in Thailand, and ordered the construction of a huge reservoir north of the capital to provide irrigation for wet rice cultivation. His son, Yasovarman I (889 - 900), built the Eastern Baray reservoir. Its dikes, which may be seen today, are more than 6 kilometers long and 1.6 kilometers wide. The elaborate system of canals and reservoirs built under Indravarman I and his successors were the key to Kambuja's prosperity for half a millennium. By freeing cultivators from dependence on unreliable seasonal monsoons, they made possible an early "green revolution" that provided the country with large surpluses of rice. Kambuja's decline during the thirteenth and fourteenth centuries probably was hastened by the deterioration of the irrigation system. Attacks by Thai and other foreign peoples and the internal discord caused by dynastic rivalries diverted human resources from the system's upkeep, and it gradually fell into disrepair. Angkorian society was strictly hierarchical. The king, regarded as divine, owned both the land and his subjects. Immediately below the monarch and the royal family were the Brahman priesthood and a small class of officials, who numbered about 4,000 in the tenth century. Next were the