The official language of the SRV is Vietnamese (Quoc ngu). A tonal language, it bears similarities to Khmer, Thai, and Chinese, and at least one-third of the vocabulary is derived from Chinese. Formerly, Vietnamese was written in Chinese characters, but under French rule a Romanized alphabet originally developed by Roman Catholic missionaries in the 17th century was adopted as the standard written form of the language. Most of the minority groups have their own spoken languages, and some have their own writing systems, but all children in the SRV today receive instruction in the national language. Other languages include Chinese, English, French, Khmer, and the tribal languages of Mon-Khmer and Malayo-Polynesian.