THAYETMYO, a district in the Irrawaddy division of Burmah, having an area of 2397 square miles, and lying between 18° 50 and 19° 30 N. lat. and between 94° 30 and 95° 50 E. long. It is bounded on the N. by the newly acquired territory of Burmah, on the E. by Toungú district, on the S. by Prome, and on the W. by Sandoway. On the west is the Arakan Yoma range, and on the east the Pegu Yoma; and the face of the country, where it does not rise into mountains, is everywhere broken by low ranges of hills, many of which are barren and destitute of all vegetation. The greater part of the district is wooded, and the Yomas east and west are covered with forests now mostly preserved. The chief river is the Irrawaddy, which traverses Thayetmyo from north to south. The country is well drained; the drainage finds its way to the Irrawaddy by three main streams (the Pwon, Ma-htún, and Ma-de) on the west, and by two (the Kye-nee and Bhwot-lay) on the east. Several salt and hot springs occur in many localities of the district; petroleum is also found, and extensive lime quarries exist a few miles south of Thayetmyo. The principal wild animals are leopards, wild cats, barking deer, elephants, rhinoceroses, tigers, black bears, and wild hogs. Silver pheasants and partridges are found in large numbers, especially in the mountains.

In 1881 the number of inhabitants in the district was 169,560 (males 87,308, females 82,252); Hindus numbered 2620, Mohammedans 1861, Christians 2349, and Buddhists 148,629. The chief town is Thayetmyo, with a population (1881) of 16,097; it is situated in 19° 18 43" N. lat. and 95° 15 40" E. long., on the right bank of the Irrawaddy. Of the total area of 1,534,080 acres, only 108,167 were under cultivation in 1885–86; 547,631 were available for cultivation; and forests occupied 256,256 acres. The chief products are rice, cotton, oil seeds, and tobacco; cutch is also very abundant, and the manufacture of the dye-stuff is carried on extensively. Coal has recently been found in the district, and earth oil-wells exist, but neither coal nor oil has yet been extracted in any quantity. The revenue of the district in 1885–86 was returned at £36,702, of which the land contributed £10,482. On the annexation of Pegu by the British in 1852–53, Thayetmyo was formed into a subdivision of Prome district; and in 1870 it was erected into a separate jurisdiction and placed under a deputy-commissioner.