Pathein, formerly called Bassein, is the largest city and the capital of the Ayeyarwady Region, Myanmar (Burma). It is located 190 km (120 mi) west of Yangon within Pathein Township on the bank of the Pathein River (Pathein), which is a western branch of the Irrawaddy River, the city had a population of 172,923 in 2019. Although once a part of the Mon kingdoms, Pathein has few ethnic Mon residents today. The majority are of Bamar with a significant Karen, Burmese Indian, Rakhine and Burmese Chinese populations.

Ayeyarwady Region is a region of Myanmar, occupying the delta region of the Ayeyarwady River. It is bordered by the Rakhine State to the northwest, the Bago Region to the north, Bago Region and Yangon Region to the east, and the Bay of Bengal to the south and west.