Taejo of Goryeo

Born in 877, Wang Kŏn rose during the chaos of the Later Three Kingdoms, a fractured peninsula locked in rival claims. In 918 he declared himself king and founded Goryeo. For eighteen years he fought and negotiated, until 936 when the last kingdom fell and the peninsula stood whole again. He ruled the unified state until his death in 943, a reign long enough to root the dynasty that would carry his work forward for four centuries.