 When the a professional K League 2 was launched in 2013, it was relegated to the fourth tier league.In 2017, it was divided into the fourth tier K3 League Advanced and the fifth tier K3 League Basic on a system of promotion and relegation.In 2020, the former Korea National League and K3 League Advanced/Basic went defunct and will got merged into the K3 League as third tier, and the rest of the K3 League Advanced/Basic clubs were founded in the K4 League.