Kpop originated from American and British music being taught in Korean schools and Korea making their own versions of it dating back to 1885. 1910-1945, Japan started gaining influence over the music. They were being oppresed by them and in the process these re-made songs(changga (창가)) became fight back songs to them. However that isn't the only way Japan influeced the industry. Korea saw that Japan had its own pop industry that had various problems with marketing, not allowing them to go global. Korea took the opertunity to outdo Japan in this sense and took over their way of doing things with small tweaks.

Thats when Big Bang and PSY got big in america, PSY's 'Gangnam Style' and Big Bang's 'Bang Bang Bang' getting big, Gangnam being the most viewed K-pop video to this day with over 3 billion views