Since the API doesn't support discovery by country yet see here: https://www.themoviedb.org/talk/56dfdf2692514125cd002054

Also if you are interested in Vietnamese cinema:

Great Directors:

Tran Anh Hung

Victor Vu

Charlie Nguyen

Ngoc Dang Vu

Dang Nhat Minh

Great Actors:

Thai Hoa

Also see here:

http://www.imdb.com/country/vdvn

http://www.imdb.com/country/vn

https://mubi.com/lists/vietnamese-cinema