Linguists do not agree where Japanese may have originated, although there are many theories ranging from Japanese being related to the extinct Goguryeo language of the Korean Peninsula to Japanese being related to Turkish (an Altaic language).
Proto-Japanese (the hypothetical first Japanese language) was spoken in Japan by the third century AD, when the clans of Japan were united into a nation under the Yamato Clan. By the sixth century AD China was having a large influence on Japanese language and culture. The Japanese writing system is entirely borrowed from China. Also, nearly forty percent of Japanese vocabulary is Chinese in origin.
Japanese language has gone through four stages: Old Japanese (from 300 AD to 800 AD), Late Old Japanese (900 AD to 1100 AD), Middle Japanese (1200 AD to 1600 AD), and Modern Japanese.
Modern Japanese
Modern Japanese has been spoken since the seventeenth century to the present. With the rise of Modern Japanese came the inclusion of more foreign loan words into the Japanese lexicon from a wide variety of languages. Words such as 'pon' for bread (Portuguese) and 'popcorn' from English.
Today, Japanese is still changing. Colloquial speech is becoming more commonplace as polite speech (which I will discuss further in a different article) is falling out of favor among young Japanese speakers. Modern Japanese has also become a popular language to learn worldwide due to the influence of Japan as a world leader in business and the popularity of anime and video games.