The basin is surrounded by low mountains, most of which are also part of Gyeongju National Park. Specifically, it is bordered by Gowi Mountain (495 m above sea level) on the south, Seondo Mountain (380 m) and Ongnyeo Peak (215 m) on the west, and Gumi Mountain (594 m) on the north. Namsan, a mountain composed of two peaks (466 m, 495 m), cuts the Gyeongju Basin into two parts at the southern end. The streams that flow from these mountains have formed a number of interlinked alluvial plains in the Basin.