Soju was first distilled around the 13th century, during the Mongol invasions of Korea. The Mongols had acquired the technique of distilling "Arak" from the Muslim World during their invasion of Central Asia and the Middle East around 1256, it was subsequently introduced to Koreans and distilleries were set up around the city of Kaesong. Indeed, in the area surrounding Kaesong, Soju is known as "Arak-ju" (hangul: 아락주). Under the reign of King Chungryeol, soju quickly became a popular drink, while the stationed region of Mongolian troops came to produce high-quality soju, for instance in Andong.