Ao Dai

In 8th grade, Tammy sang in her school chorus. During concerts, girls wore the ao dai, a traditional dress for Vietnamese women. 
According to Vietnamese tourism.org, ao dia are originally from the Nguyen Dynasty, but, have taken on many variations since the ao dia's first appearance in the 18th century.  The color of the ao dia also has a significant meaning, young girls will often wear white, while colors are worn by married women. 

Ao dia are also used for musical occasions. Tammy wore them for school chorus concerts. A link to some traditional Vietnamese music has been provided the women on the right is wearing a red and white ao dia.
https://www.youtube.com/watch?v=WQse9mJ1Tuc#action=share

According to Vietnamese tourism.org, traditional Vietnamese music is influenced by traditional Chinese and Cambodian music, most likely because of the trade routes shared between the three countries.

Reference

vietnamtourism.org. (2011, November 16). Ao di vietnam and its history. Retrieved from vietnamtourism.org: https://www.vietnamtourism.org.vn/attractions/culture/vietnamese-costume/ao-dai-vietnam-and-its-history.html