A remarkable feature of Southeast Asia is the different ways people have adapted to local environments. In premodern times many nomadic groups lived permanently in small boats and were as orang laut, or sea people. The deep jungles were home to numerous small wandering groups, and interior tribes also included fierce headhunters. In some of the islands of eastern Indonesia, where there is a long dry season, the fruit of the lontar palm was a staple food; in other areas, it was sago. On the fertile plans of Java and mainland Southeast Asia sedentary communities grew irrigated rice; along the coasts, which were less suitable for agriculture because of mangrove swamps, fishing and trade were the principal occupations. Due to a number of factors—low populations, the late arrival of the world religions, a lack of urbanization, descent through both male and female lines—women in Southeast Asia are generally seen as more equal to men that in neighboring areas like China and India.
Cultural changes began to affect Southeast Asia around two thousand years ago with influences coming from two directions. Chinese expansion south of the Yangtze River eventually led to the colonization of Vietnam. Chinese control was permanently ended in 1427, but Confucian philosophy had a lasting influence when Vietnam became independent. Buddhism and Taoism also reached Vietnam via China. In the rest of mainland Southeast Asia, and in the western areas of the Malay-Indonesian archipelago, expanding across the Bay of Bengal meant Indian influences were more pronounced. These influences were most obvious when large sedentary populations were engaged in growing irrigated rice, like northern Vietnam, Cambodia, Thailand, Burma, Java, and Bali. Rulers and courts in these areas who adopted Hinduism or forms of Buddhism promoted a culture which combined imported ideas with aspects of local society.
Differences in the physical environment affected the political structures that developed in Southeast Asia. When people were nomadic or semi-nomadic, it was difficult to construct a permanent governing system with stable bureaucracies and a reliable tax base. This type of state only developed in areas where there was a settled population, like the large rice-growing plains of the mainland and Java. However, even the most powerful of these states found it difficult to extend their authority into remote highlands and islands.