Seoul is located at 126 degree 59 minutes east longitude, 37 degree 34 minutes north longitude in the mid-western region of the Korea Peninsula. Seoul proper comprises 605.39 km² of area, roughly bisected into northern and southern halves by the Han River. The Han River and its surrounding area played an important role in Korean history. The Three Kingdoms of Korea strove to take control of this land, where the river was used as a trade route to China (via the Yellow Sea). However, the river is no longer actively used for navigation, because its estuary is located at the borders of the two Koreas, barred for entrance by any civilian. The city is bordered by eight mountains, as well as the more level lands of the Han River plain and western areas.