LITTLE IS KNOWN of the earliest inhabitants of what is now Thailand, but 5,000-year-old archaeological sites in the northeastern part of the country are believed to contain the oldest evidence of rice cultivation and bronze casting in Asia and perhaps in the world. In early historical times, a succession of tribal groups controlled what is now Thailand. The Mon and Khmer peoples established powerful kingdoms that included large areas of the country. They absorbed from contact with South Asian peoples religious, social, political, and cultural ideas and institutions that later influenced the development of Thailand's culture and national identity