Wikipedia
Sageuk in Korean denotes "historical dramas", including traditional drama plays, films or television series. In English language literature sageuk usually refers to historical films and television series (of South Korea).
The first known historical film, The Story of Chun-hyang was made in 1923, directed by a Japanese filmmaker. The first Korean sound film was also sageuk. The heyday of Korean cinema began in the 1950s and lasted until the 1980s, with many sageuk films released, like Lee Gyu-hwan's Chunhyang adaptation in 1955. In the 1960s, historical melodramas were significant, as well as martial arts films. In the 1970s, due to the popularity of television, cinema started to decline, and in the 1980s it encountered a crisis, which prompted filmmakers to try to win viewers back with erotic pieces. From the 1990s, Im Gwon-taek's movies, as well as The Legend of Gingko and The Eternal Empire are significant works. From the 2000s, sageuk films started flourishing, between 2012 and 2015 Korean cinema produced five sageuk that broke the 10 million viewership record. As of 2016 June, the highest grossing South Korean film is also a historical drama: The Admiral: Roaring Currents.
The first television series, a sageuk, of South Korea aired on state channel KBS in 1962, titled Gukto malli. In the 1970s, in contrast to the previous decade, historical TV series portrayed national heroes like Yi Sun-shin or Sejong the Great. The characteristic series of the 1980s was Joseonwangjo 500 nyeon ("500 Years of Joseon"). The 1990s were dominated by contemporary dramas with regards to popularity and viewership ratings, despite having produced a number of quality sageuks. The 2000s saw the birth of the "fusion sageuk" genre, which changed the historical series genre in South Korea. Some of the significant works from this period are Hur Jun, Damo and Dae Jang Geum.
Popular themes of sageuks include elements from Korean folklore and mythology, famous or notorious princes, kings, national heroes and famous women.