Mawlamyine, formerly Moulmein, is the fourth-largest city in Myanmar, 300 kilometres south east of Yangon and 70 kilometres south of Thaton, …Mawlamyine, formerly Moulmein, is the fourth-largest city in Myanmar, 300 kilometres south east of Yangon and 70 kilometres south of Thaton, at the mouth of Thanlwin River. Mawlamyine was an ancient city and the first capital of British Burma. The city is currently the capital and largest city of Mon State and the main trading centre and seaport in south eastern Myanmar.