Vietnam has around 80 million inhabitants and is one of the most densely populated countries in the world. Just 20% of the population live in the city. Around 3 million people live in the capital city, Hanoi, and around 6 million in Ho Chi Minh City (formerly Saigon). The deltas of the Mekong and the Red River are extremely densely populated, while the hilly and mountainous regions are sparsely populated. The population is relatively young, with over half under 21. Vietnam has a large number of ethnic groups; the largest is the Kinh (88%), ethnic Vietnamese. The one million Chinese form an important minority. Only 3000 of these have chosen to keep their Chinese nationality, while the rest (referred to as the Hoa) have taken official Vietnamese nationality. In general, the ethnic Chinese, with or without Vietnamese nationality, follow Chinese customs and dress style. Many ethnic Chinese reside in Cholon; a prospering trade centre 2.5 miles from the centre of Ho Chi Minh City. Over 50 ethnic minority groups live in the mountainous regions, which constitute around two thirds of the total land area of Vietnam. These groups, referred to by the French as montagnards (mountain-dwellers), include the Muong, the Ra Dé, the Ja-rai, the Banhar and the Sedang in central Vietnam, and the T-y, N-ng, Thài, Hmong, Lao and the Lu in northern Vietnam. There are also the Cham and Khmer, with Cambodian roots who, live predominantly in the Mekong Delta. The Vietnamese government is currently striving for more integration of the ethnic groups into Vietnamese society. The official language is Vietnamese, which uses the Roman alphabet, and is a tonal, monosyllabic language. The meaning of a word is governed by the tone (one of 6 separate tones) in which it is pronounced. Many of the various ethnic groups also speak their own language.