"Korea" derives from the Goryeo period of Korean history, which in turn referred to the ancient kingdom of Goguryeo, the first Korean dynasty visited by Persian merchants who referred to Koryŏ (Goryeo; 고려) as Korea. Koryŏ (Goryeo) is also the name of Goguryeo, which changed its name to Koryŏ (Goryeo) in the 5th century (during the reign of King Jangsu of Goguryeo). Korea is now commonly used in English contexts by both North and South Korea. In the Korean language, Korea as a whole is referred to as Han-guk (한국) in South Korea, and Chosŏn (조선) in North Korea. The latter name, also Romanised Joseon, is from the Joseon Dynasty and the earlier Gojoseon. "The Land of the Morning Calm" is an English language title for the country loosely derived from the hanja characters for Joseon.