Founded by the same rebels that Destroyed the Silla Kingdoms, the Koryo Dynasty was created in the Year AD 935 and would last around 457 years until it was conquered by the Mongol Empire. The Koryo Dynasty is the name from which "Korea" is derived.
The Koreans of course had many great achievements over their long rule. For Example, the created metal moveable type based on the original wooden carved block typing letters. They also created Celadon pottery that would become so popular that it rivaled the Porcelain pottery. And finally, The Koreans, like many other Empires of the time, were invaded and destroyed by the powerful Mongols of the Yuan Dynasty.