Who did Korea colonize?

Jizi (Gija) from Zhou dynasty colonized Korean peninsula first at 11th century BCE, after that, Emperor Wu of Han conquered Korean peninsula and established commandery called Lelang in Pyongyang in 108 BC. Korea was also conquered by Mongolian and governed by Yuan Dynasty. Korea was part of China until became totally independent from Mainland china after 1895, but they colonized again by Japan during 1910-1945.