Sĩ Liên). According to Nayan Chanda, the Vietnamese had adopted Sinocentric views towards their surrounding neighbors such as the Chams and Cambodians, and considered non-Sinospheric cultures as barbaric. David G. Marr noted that a possible reason for social stratification, such as with the Montagnards and the Việt, were that other ethnic groups did not share the same passion for wet-rice cultivation as the Vietnamese Kinh people did. By the Nguyễn dynasty the Vietnamese themselves were ordering Cambodian Khmer to adopt Han culture style by ceasing habits like cropping hair and ordering them to grow it long besides making them replace skirts with trousers. Han Chinese Ming dynasty refugees numbering 3,000 came to Vietnam at the end of the Ming dynasty. They opposed the Qing dynasty and were fiercely loyal to the Ming dynasty. Their descendants became known as Minh Hương. They did not wear Manchu hairstyle unlike later Chinese migrants to Vietnam during the Qing dynasty. Both the Lingnan and historical Northern Vietnamese cultures are similar in possessing Nanyue and Han Chinese culture. Holidays and other important days Vietnam celebrates many holidays, including traditional holidays which have been celebrated in Vietnam for thousands of years, along with modern holidays imported predominantly from western countries. Among the traditional holidays, the two most important and widely celebrated are the Lunar new year (Tết), followed by the Mid-autumn lantern festival (Tết Trung Thu), although the latter has been losing ground in recent years. Public holidays Other holidays World and intangible cultural heritage Vietnam has a number of UNESCO-listed World Heritage Sites, as well as cultural relics deemed as intangible heritage. These are split into specific categories: Cultural heritage sites Hội An: An ancient city and trading centre. Imperial city of Huế: Complex of monuments in the former imperial capital. Mỹ Sơn: Ancient temple complex of the former Champa civilization in Quảng Nam Province. Imperial Citadel of Thăng Long: Hanoi old city One Pillar Pagoda: The pagoda is a historic Buddhist temple in the central Ba Đình district (near the Imperial Citadel of Thăng Long), Hanoi, the capital of Vietnam Natural heritage sites Phong Nha Cave located in Quảng Bình Province Hạ Long Bay Đồng Văn Karst Plateau Geopark Intangible cultural heritage Nhã nhạc: a form of Vietnamese court music Cải lương: Southern Vietnam-styled opera Space of gong culture Ca trù Quan họ There are a number of other potential world heritage sites, as