It is said that in 1100 copper cash had begun to circulate for the first time with freedom among the people. Buddhism also made material advances during this reign and riveted its fetters more firmly upon the body politic. On the whole it was a very clean reign, when we remember that a usurper was on the throne.
In 1106 Suk-jong’s son U, posthumous title Ye-jong, came to the throne. At the very first he was confronted by a new problem. The people had yet to learn that the coinage of money is a purely government monopoly. The readiness with which cash circulated tempted some to attempt to counterfeit it. The king consequently promulgated a law inflicting a heavy penalty upon this offense and at the same time made a law against the adulteration of food.
Having, in his third year, married a near relative he took as a teacher a monk named Un-jin, another indication of the steady progress of that cult. The talk about the change of site for the capital resulted in the building of a palace at P‘yŭng-yang and several royal progresses to each of the proposed sites.
The tribe of Yŭ-jin had repeatedly promised to remain peaceful and had as often broken their word; so now when they began to grow restless again, the king decided to make an end of the matter. He sent a strong force into their territory, killed 4,800 men and took several thousand prisoners. The territory was divided into four administrative districts.
In 1115 the king developed a fad. He became an enthusiastic botanist. He ransacked the kingdom for rare and beautiful plants and sent them to China in exchange for many kinds that were not indigenous.
We have now arrived at the threshold of events which were destined to result in the founding of a great dynasty. In order to explain we must go back a few years. Early in this dynasty a Koryŭ monk from P‘yŭng-yang, named Keum-jun, had fled, for some reason not stated, to the town of A-ji-go among the Yŭ-jin tribe. He had there married a Yŭ-jin woman and gotten a son whom he named Ko-eul. He in turn begot Whal-ra, and to him were born many sons, the eldest of whom was Hyo-ri-bal and the second Yong-ga. The latter was unusually bright and popular and eventually became chief; but on his death the son of his brother Hyo-ri-bal, named O-a-sok, took his place. O-a-sok died and his younger brother, A-gol-t‘a, became chief. Yŭ-jin was at this time a small weak tribe under the sway of the Ki-tan court, but now the masterly genius of A-gol-t‘a had come to her help, matters were destined to assume a different complexion.