Then singing is a folk music genre of the Choang, Tay and Nung ethnic groups. This kind of singing has the sound of the epic genre and has a religious nuance. It recounts the journey to heaven to beg the Jade Emperor to solve people problems. The series "The Then singing of the Tay, Nung and Thai ethnic groups in Vietnam" was compiled to provide readers with an overview of the Then heritage with the contents of introducing the general appearance, the distribution of the heritage from the perspective of geography. The content of the lyrics in the Then rituals introduced in the book series are recorded, transcribed, and translated from the audio and image documents collected by the Vietnam Academy of Music during field collection . This brings the authenticity and objectivity of the material to the book series. The second book contains the lyrics of the Then rituals of the Tay people in Cao Bang, Bac Kan, Lang Son.