During the period of Goryeo under Mongol rule, which lasted from about 1270 to 1356, the Korean Peninsula was effectively under the dominion of the Mongol Empire and the Mongol-led Yuan dynasty. This era began with the Mongol invasions of Korea, which included six major campaigns between 1231 and 1259. These invasions resulted in the annexation of northern Korean territories by the Mongols, who established Ssangseong Prefecture and Dongnyeong Prefecture.

Following the invasions, Goryeo became a semi-autonomous vassal state and a compulsory ally of the Yuan dynasty. Members of the Goryeo royal family were married to spouses from the Yuan imperial clan, solidifying their status as imperial sons-in-law. Goryeo's rulers were allowed to govern as vassals, and the Yuan established the Branch Secretariat for Eastern Campaigns in Korea to oversee Mongol supervision and political power in the region.

Throughout this period, intermarriage between Koreans and Mongols was encouraged, leading to a close relationship between the two dynasties. Korean women entered the Mongol Empire as war booty, and Korean elites were married to Mongol princesses. Goryeo's kings held a unique status within the Mongol imperial hierarchy, akin to other important families of conquered or client states.

The Branch Secretariat for Eastern Campaigns played a significant role in administering Goryeo and maintaining Mongol control. While Goryeo retained some autonomy in conducting its own government, the Branch Secretariat ensured Mongol influence in various aspects of Korean governance, including the imperial exams.

Over time, Goryeo's relationship with the Yuan dynasty evolved. King Gongmin of Goryeo began to push back against Mongol garrisons in the 1350s, coinciding with the decline of the Yuan dynasty in China. Ultimately, Goryeo severed its ties with the Mongols in 1392, leading to the establishment of the Joseon dynasty.

Under Mongol rule, the northern defenses of Goryeo were weakened, and the standing army was abolished. The Mongol military system, known as the tumen, was introduced to Goryeo, with Goryeo soldiers and officers leading these units. Korean culture also experienced significant influence from Mongol customs, including clothing, hairstyles, cuisine, and language. Economically, Yuan paper currency entered Goryeo's markets, leading to inflationary pressure. Trade routes connected Goryeo to the Yuan capital, Khanbaliq, facilitating the exchange of goods and currency.