Modern Korea's beginnings can be traced to the three-kingdom unification under the Silla Kingdom in 688 AD, and the subsequent Goryeo and Joseon Dynasties, which ruled the present-day boundaries of the nation as the Korean Empire, until its annexation by a growing Japan in 1910. For thirty-five years, Korea was ruled by Japanese military authority, until the southern half of the peninsula was liberated by Western Allied (mainly American) troops in late 1945, on the heels of Japan's surrender. Korean subservience to Japan for so long fostered some mistrust of American troops in the years following the liberation, which only led to greater confusion in early 1950 when North Korea, a communist state established in the Soviet-occupied half above the 38th parallel launched an invasion of the so