The Tằng Cẩu ceremony in Black Thai weddings.

The Tang Cau ceremony (also known as "Khun Cau") is an important and special ritual in the weddings of the Black Thai people in Northwest Vietnam. This ceremony involves tying the bride's hair up on top of her head, marking the transition from a single woman to a married woman.

The Tằng cẩu ceremony is the clearest sign that a Black Thai woman is married. After performing this ritual, the bride officially becomes a member of her husband's family and takes on new responsibilities.

Today, despite cultural changes and influences, the Tang Cau ceremony is still preserved by many Black Thai families, especially in rural areas. It is not only a wedding ritual but also a symbol of beauty, maturity, and responsibility for Black Thai women.