Mu-hyŭl, the third king of Ko-gu-ryŭ died in 45, leaving the kingdom to the tender mercies of his son a worthless debauchee. Four years later he in turn made way for Hă-u, a member of a collateral branch of the family. Following the traditions of Ko-gu-ryŭ this ruler professed loyalty to China on the one hand and seized all the Chinese territory he could lay hands on, on the other. In 54 he was assassinated by one Tu-no and the seven year old grandson of king Yu-ri was placed on the throne, a regent being appointed to carry on the government until the boy reached his majority. The good work continued. Ten forts were built in western Liao-tung to guard against Chinese advances, which shows that she had regained nearly all the territory she had lost at the hands of the parvenu Wang-mang. The following year she took formal possession of the territory of Ok-jŭ on the eastern coast.
In the year 58 Yu-ri, the third king of Sil-la died. He must not be confounded with Yu-ri the second king of Ko-gu-ryŭ. The sound is the same but the character is different. It was he who had the difference of opinion with Sŭk-t’al-hă in regard to the succession. As he died without issue the reins of government naturally passed into the hands of the aged statesman Sŭk-t’al-hă. He was sixty-two years old when he assumed the cares of royalty. In his fifth year the one remaining Ma-han chief, Măng-so, who had escaped the appetite of Păk-je, went over to Sil-la, as he concluded it was no longer possible to prolong a hopeless struggle against Păk-je. Pok-am fortress thus passed into the hands of Sil-la. Strange to say Păk-je not only did not resent this but even made overtures to Sil-la for a friendly meeting of their respective kings in the following year. Sil-la refused to sanction this, and the rebuff was too much for the equanimity of Păk-je. From that day the attitude of Păk-je toward Sil-la was one of studied hostility, broken only by an occasional spasmodic attempt at reconciliation. Among the three kingdoms, Sil-la was the only one that preserved her dignity intact and kept herself untainted by the charge either of avarice or pusilanimity.
The year 66 brought forth another of those wonders that embellish the legendary lore of Korea. The king of Sil-la was wakened one night by the loud cackling of a hen, which seemed to come from a forest to the south. A messenger was sent to see what was the cause of the disturbance and he found a box hanging from the branch of a tree, while on the ground beneath it there cluttered a white hen. When the box was placed before the king and he had opened it a handsome child was found. It received the name Keum Yun-ji. Some say this Yŭn-ji was merely a part of the name while others affirm that it is a pure Sil-la word meaning “baby”. Up to this time the kingdom had been called Sŭ-ra-bŭl but now the king changed it to Kye-rim, _kye_ meaning “hen” and _rim_ meaning “woods.” So the kingdom was called “Hen in the Woods”, not a very dignified name but one, perhaps, that fitted well the military prowess of the kingdom.