Trot music from Korea is their oldest form of pop music, taking it's name from the foxtrot ballroom dance which has the same kind of simple 4/4 beat. It seems to a 20th century music, and was starting to die out until a recent revival by a few pop stars.
Here's some classic old Trot from the war era. This is a bit grim, but bear with me - tomorrow we'll have some of the happy modern stuff. Strangely the accordion is one of the typical instruments for Trot.