Like many other traditional costumes of Vietnam, Non la has its own origin, coming from a legend related to the history of rice growing in Vietnam. The story is about a giant woman from the sky who has protected humankind from a deluge of rain. She wore a hat made of four round shaped leaves to guard against all the rain. After the Goddess was gone, Vietnamese built a temple to commemorate her as the Rain-shielding Goddess.

Among conical hats, the nón lá of the Vietnamese people forms a perfect right circular cone which tapers smoothly from the base to the apex. Special conical hats in Vietnam contain colourful hand-stitch depictions or words while the Huế varieties are famous for their nón bài thơ (literally: poem conical hats). These contain random poetic verses and Hán tự which can be revealed when the hat is directed above one's head in the sunlight. Today, it has become part of Vietnam's national costume.