The Tày language is widespread within Vietnam, but particularly concentrated in the northern provinces. Tày is similar to the Nùng language, and has several dialects, including Northern Tày, Tày Trùng Khánh, and Tày Bảo Lạc. It is spoken by the Tày people, the largest ethnic minority group in Vietnam (the Kinh are not categorized as an ethnic minority). The 168,719 Tày people of Hà Giang comprise over 23% of the population of the province. Despite being so widespread, the language is threatened, as many Tày people no longer speak Tày, and instead learn Vietnamese as their first language. Literacy in the Tày language is less than 5% among ethnic Tày.The Tày are people of the valleys and plains, and usually live near the bottom of a mountain. They live in small villages made up of thatch-roofed stilt houses surrounded by rice paddies. Wet rice cultivation is very important in Tày society, and they have developed sophisticated irrigation methods for flooding their fields. Many Tày people practice a traditional folk religion called Then, which involves worshiping ancestors and god of the environment. The traditional Tày ethnic dress consists of cotton clothes dyed with dark blue patterns using indigo plants, complemented with silver necklaces and silver bracelets and anklets. They are famous for their intricately patterned brocade weavings.