Where the rainfall is greatest, broad-leaved evergreen rain forests are common. Where there is less rainfall, the forests have trees that lose their leaves in the dry season. Teak is the best known of these trees. In prehistoric times the dry zone was a savanna, with mixed grass and trees. Most of the delta, formerly a swamp forest, has been cleared for farms.
Mangrove forests rim the delta and portions of the coasts.
The population of Myanmar is more than 40 million. Most of the ancestors of the present population came originally from southwestern China about 2,000 years ago. The various groups spoke different languages and had different customs, but the people were predominantly of Mongoloid background. The country's name change from Burma to Myanmar in 1989 was made to make clear the fact that the country was composed of various ethnic groups, not just the majority Burmans. The Burmans make up almost three quarters of the population and live chiefly in the central lowlands and the delta.