In addition to these two indigenous language families, there is Japanese Sign Language as well as significant minorities of ethnic Koreans and Chinese, who respectively constitute approximately 0.5% and 0.4% of the country's population and many of whom continue to speak their respective ethnic language in private contexts (see Zainichi Korean). There is also a notable history of use of Kanbun (Classical Chinese) as a language of literature and diplomacy in Japan, similar to the status of the Latin language in medieval Europe, which has left an indelible mark on the vocabulary of the Japanese language. Kanbun is a mandatory subject in the curricula of most Japanese secondary schools