People of U-san State lived on Nari basin during Shilla Dynasty. But the basin was left empty for hundreds of years due to the empty-island policy (a policy restricting anyone to inhabit on the island) during Joseon Dynasty. Later, people began to re-settle on the island after King Gojong abandoned the policy. The area was called Nari because Ullueng-do lily were abundant when the first settlers arrived on the island. A primeval forest is a forest that has attained great age without significant disturbance and thereby exhibits unique ecological features. On July 11th, 1967, Seonginbong Primeval Forest, located near the peak of Seonginbong, was designated as Natural Monument (no. 189) as the forest is home to rare plants, grown only in Ullueng-do. The rare plants were able to grow, thanks to geographical and geological features of the island. It is estimated that isolation from the main land and pumice deposits, accumulated from the latest volcanic eruption, created the environment for the rare plants to grow on the island. Ullueng-do, composed mainly of hard volcanic rocks, provides poor environment for soil formation or plant growth. However, Ulleung-do is now covered with pumice, formed by the last volcanic eruption. Weathering and erosion of pumice over a long period formed nutrient-rich soil, providing suitable conditions for plants to grow.