During King Myeongjong's reign in Joseon, two major political factions vied for power: the Greater Yun, led by Yun Im, and the Lesser Yun, headed by Yun Won-hyeong and Yun Won-ro. Though related, these factions engaged in a bitter struggle for dominance. Initially, in 1544, the Greater Yun faction rose to prominence under Yun Im's leadership when Injong ascended the throne. However, their failure to eliminate the opposition, safeguarded by Queen Munjeong, led to their decline.

After King Injong's death in 1545, the Lesser Yun faction, supported by Queen Munjeong, gained the upper hand. They orchestrated the Fourth Literati Purge in 1545, resulting in the execution of Yun Im and many of his followers, significantly weakening the Greater Yun faction. Yun Won-hyeong's rise to power within the Lesser Yun faction was marked by further political purges. In 1546, he impeached and executed his brother Yun Won-ro and consolidated his power, eventually becoming the Chief State Councilor in 1563. Despite his brutal rule, Queen Munjeong effectively administered the kingdom, redistributing land to the commoners.

The death of Queen Munjeong in 1565 was a turning point. Myeongjong, then at the age of 20, began to assert his rule. He executed Yun Won-hyeong and his second wife, Jeong Nan-jeong, who had gained significant influence through her close ties to the queen. Yun Won-hyeong's reign had been marked by corruption and governmental instability, leading to rampant threats from Jurchens, Japanese forces, and internal rebellions. Myeongjong attempted government reforms by reinstating exiled Sarim scholars. However, he passed away in 1567 without a male heir. His half-nephew, Yi Gyun (later King Seonjo), was adopted by Queen Dowager Uiseong to succeed him.