Korean is spoken by approximately 78 million people worldwide, the vast majority of whom live in South Korea (Republic of Korea) and North Korea (Democratic People's Republic of Korea). Korean is the national language of both countries. Nearly two million Korean speakers also live in China and additional groups can be found in Japan and the United States.
Korean is rarely mentioned in history books before the 15th Century, but linguists have a good understanding of the language starting with Middle Korean, whose formation coincides with the invention of the Korean script in 1444. It is assumed that Korean is a descendant of the Altaic group of languages, which includes Turkish, Mongolian and Tungus. However, there is also evidence that Korean is related to Japanese.
Korean has borrowed extensively from Chinese and over half of the Korean vocabulary comes from Chinese. It also has borrowed words from Mongolian, Sanskrit, German and English.
The standard spoken language in South Korea is called Pyojuneo or Pyojunmal and is based on the dialect spoken in the capital city of Seoul and the surrounding areas. North Korea's standard spoken language is similarly based on the dialect spoken in its capital, Pyongyang.