Before Chinese influence, in hot days we would wear loincloths and the women would wear skirts.
But in cold days we would wear overalls though. So depending on the temperature, we would be skimpy on hot days and wear overalls on cold days.
http://www.nhandan.org.vn/english/history/20001014.htmlQUOTE
As for clothing, men wore loincloths and women wore skirts of various types. When it was hot, the inhabitants kept themselves half-naked, and when it was cold, they wore overalls (which looked like a blanket with a hole in the middle). They had their hair cut short, twisted in bun or grown long behind the back. They wore a scarf around the head all year round and kept their feet bare. Boys and girls wore jewellery made of precious stone or brass. Fishermen had their body tattooed.