The traditional áo dài is Vietnam's national, two-piece dress. It is fitted from the waist-up and the rest of the dress is loose. On formal occasions, matching circular headgear, khăn đóng, is also worn.
A while ago I was asked about the construction of the Vietnamese Ao Dai and Chinese Cheongsam/Qipao. I had a few dresses at my disposal and figured it w. the difference between Ao Dai and Cheongsam/Qipao