For decades, there have had many debates about the Ngai people in Vietnam. Some people think that the Ngai people are Chinese, or a branch of the Chinese people based on cultural similarities and customs. However, it was not until the late 70s of the last century that the Ngai ethnic people, with elaborate studies of researchers, were identified in the 54-ethnic-group community in Vietnam. At the same time, it was also pointed out that the Ngai and the Chinese are two independent communities with different languages and modes of production.

A Ngai woman (the one with black outfit) in Nguyên Bình, Cao Bằng

Despite having different names like Ngai Hac Ca, Sin, Đan and Le, its favourite one is San Ngai, which means "mountainous people". The name implies not only the topography of the place where they live, but also the affirmation that they are one of the groups who discovered and created villages in the high mountainous areas where Ngai people once lived. Many years ago, the Ngai lived together in villages in which each village had a patriarch who had the right to decide and run all the big and small stuff in the village. Nowadays, the Ngai live together with the Tay, Nung, Kinh, and Dao in Pac Man hamlet in Nguyen Binh district (Cao Bang). In addition to rice and maize cultivation, the Ngai here are also known for their traditional noodle rice paper making. Their noodles are supplied to most local eateries because it is thought that the noodles they serve are the best. According to preliminary statistics in Cao Bang province, the Ngai live mainly in Nguyen Binh town and Tam Kim commune, Nguyen Binh district. Traditional Ngai costumes are quite simple. Ngai women often wear 5-body shirts with buttons on the right and men wear indigo-colored pocket shirts and kind of wide and straight leg pants with deep crotch and large waistband. However, today we rarely see many Ngai people wearing traditional costumes in their daily activities. In the past, a couple, when getting married, had to undergo two rituals, the wedding ceremony and the bedding ceremony. In addition, the groom's family always took the initiative to find a girl to propose to his son.

The custom of Ngai people in Pac Man, Nguyên Bình (Cao Bằng) is basically similar to other local peoples'

Years ago, most of the Ngai's houses were Trinh Tuong houses (traditional made-of-clay houses that are popular in Vietnam’s northern region) which were built with a special architecture showing their closed, independent lifestyle. Today, the Ngai live in four-level wooden houses depending on the actual economic conditions of each household. In spite of not a stilt house, the Ngai's house, with beautifully curved and carved columns, is still designed with a loft to have more living area. Although the old architecture is no longer maintained, they still keep the traditional house style which is a combination of a main house, a kitchen and cattle sheds built separately. The layout of the house is still preserved according to the old tradition with the family's altar placed in the main room of the house. Despite facing the risk of cultural and customary recession, the Ngai in Pac Man still use their language in the daily life as well as in folk songs and traditional love songs (known as Suong Co or Xuong Ca).

Over time and many historical events, the Ngai whose cultural features still retained to this day still prove their presence in the 54-ethnic-group community in Vietnam.