Hi Kubur,
If you check out this link you will note that Burma has been called Burma for centuries, and as far as I can see from the Wiki history it has never been called Bassein. Therefore one can not use the counties name change, as stated in your reply to Ian, as a dating aid to your dha. The country is of course now called Myanmar. Like others I would date your dha as LATE 20th c at the earliest.
https://en.wikipedia.org/wiki/History_of_Myanmar
Stu