Dan Bau is one of the typical traditional musical instruments of Vietnamese folk music and a unique instrument in the world due to its simple construction, yet it produces a variety of enchanting sounds. These captivating tones are created by the harmonics of a single string.
There is no precise documentation of the exact time when Dan Bau was introduced. However, references to the appearance of Dan Bau can be traced back to the "Đại Nam thực lục tiền biên," written in 1770 during the Nguyễn dynasty. Additionally, there are some legends about Dan Bau in the folklore of Vietnam.
Dan Bau is considered the original musical instrument of Xẩm singing art in Vietnam. Xẩm is an art form that originated from blind musicians singing to beg for money on the streets of northern Vietnam and later evolved into a performing art presented on stages. Today, Dan Bau has found its place in various roles within musical ensembles, orchestras, and traditional Vietnamese theaters, and it consistently represents Vietnam in symphonies and large-scale performances worldwide. 

The standard open string of the Dan Bau (without pressing the fret) is usually the note C3 (C3 on the piano).

In various traditional Vietnamese music genres, there are different stringing methods for the Dan Bau to match the singing voice and harmonize with other instruments. It's common to string it to the note D3 (D3), or sometimes Bb2 (Bb2) or A2 (A2). (Depending on the tuning system).

During performances, to suit different music genres, comply with the composer's requirements, or to facilitate playing, the instrument can be strung with various notes, but the most commonly used are still C3, followed by D3.