You might aware that one of the telecommunication company hire a Thai lady for their head of Human Resource team.
Myanmar national or expat , its depend on company how much they invest on development of each sector, for example the local liquar manufacturing company, 100% owned by myanmar
national have been hired a Singaporean as Director of Human Resources for more than 7 years, currently there are two expat at their Human Resources department. Another expat at manufacturing and another expart at Finance department.
For my humble opinion, most of them invest on the hightest position at each department for long time and other for short time if there is a good candidate who can take over that position after a period of working toegther with that short time contract guy.