Ahmed Sanjar vs Taejo of Joseon

Ahmed Sanjar was defeated by the Kara Khitai at the Battle of Qatwan near Samarkand. This defeat ended Seljuk dominance in Transoxiana and led to the loss of Khorasan to the Kara Khitai, marking the beginning of the Seljuk decline.

Oghuz Turk tribes in Khorasan revolted against Sanjar's rule, capturing him in battle. Sanjar was held captive for three years, during which the Oghuz plundered Khorasan and destroyed Seljuk authority in the region.

Sanjar escaped Oghuz captivity in 1156 and returned to Merv, but his authority was shattered. He died the following year, and his death marked the end of the Great Seljuk Empire, as his successors could not reunite the fragmented territories.

General Yi Seong-gye defeated a Japanese pirate (wokou) force at Hwangsan. This victory enhanced his military reputation and demonstrated his capability as a commander.

General Yi Seong-gye, ordered to invade the Ming dynasty's Liaodong region, turned his army back at Wihwado Island. This act of defiance against the Goryeo court led to a coup that eventually brought him to power.

Taejo implemented the Gwajeon Law, a land reform that redistributed land from the old Goryeo aristocracy to his supporters and the state. This weakened the old elite and strengthened the new Joseon ruling class.

Yi Seong-gye deposed the last Goryeo king and founded the Joseon dynasty, with its capital at Hanyang (modern Seoul). He established a new ruling class based on Confucian ideology, replacing the Buddhist-influenced Goryeo system.

Taejo of Joseon ordered the compilation of the Gyeongguk Daejeon, a comprehensive legal code that established the administrative and social structure of the Joseon dynasty. This code remained in effect for centuries.