Ayeyarwady (ī´yärwäd´ē) or Irrawaddy (Ĭrəwŏd´ē), chief river of Myanmar, c.1,000 mi (1,600 km) long, formed by the confluence of the Mali and Nmai rivers in N Myanmar. The combined stream flows south through gorges strewn with rapids past Myitkyina, Bhamo, Mandalay, Pakokku, and Pyay; it receives the Chindwinn River, its principal tributary, just above Pakokku. The vast Ayeyarwady delta (c.200 mi/320 km wide), one of the world's great rice-producing regions, begins at Hintada, c.180 mi (290 km) from the Andaman Sea. On a mouth of the Ayeyarwady is the capital and port of Yangon. The Ayeyarwady is one of the great rivers of Asia and serves as the economic lifeline of Myanmar. It is navigable by steamers to Bhamo (c.650 mi/1,050 km upstream) and by launches up to Myitkyina. For many centuries it was Myanmar's principal communication route.