Ivan Asen I of Bulgaria vs King Gojong of Goryeo

Ivan Asen I, along with his brother Peter, led a rebellion of Bulgarians and Vlachs against Byzantine rule. The uprising began after the brothers demanded a pronoia (land grant) from Emperor Isaac II Angelos and were refused. They proclaimed the restoration of the Bulgarian Empire, sparking a war that would eventually liberate much of Bulgaria.

Ivan Asen I and his brother Peter proclaimed the restoration of the Bulgarian Empire in the city of Tarnovo. They declared themselves emperors (tsars), claiming continuity from the First Bulgarian Empire. This act established the Second Bulgarian Empire, with Tarnovo as its capital. The proclamation was accompanied by the consecration of a new patriarch.

Ivan Asen I's forces ambushed and defeated a Byzantine army under Emperor Isaac II Angelos in the Tryavna Pass. The Byzantines were caught in a narrow mountain pass and suffered heavy losses. This victory secured Bulgarian control over the Balkan Mountains and forced the Byzantines to recognize the Second Bulgarian Empire's existence.

Ivan Asen I was assassinated by his cousin Ivanko, who had been accused of plotting against him. The murder occurred during a hunting trip. Ivanko briefly seized power but was soon overthrown by Peter, Ivan's brother. This assassination destabilized the new empire and led to a period of internal conflict among the Asen dynasty.

The Mongol Empire under

After the murder of Mongol overseers, the Mongols launched a second invasion. General Saritai led the attack. Goryeo forces resisted fiercely, but the Mongols devastated the countryside. The invasion ended when Saritai was killed by a Buddhist monk.

King Gojong moved the royal court and government to Ganghwa Island, a fortified location in the Han River estuary. This relocation was intended to resist Mongol demands and protect the monarchy. The court remained there for nearly 30 years.

The Mongols launched a third invasion, focusing on destroying Goryeo's ability to resist. They ravaged the mainland while the court remained on Ganghwa. After years of war, King Gojong agreed to peace terms in 1238, including sending a prince as hostage.

To invoke Buddhist protection against the Mongol invasions, King Gojong ordered the carving of a new set of the Tripitaka Koreana woodblocks. This massive project was completed in 1251, creating a cultural treasure that survives to this day.

After decades of war, King Gojong finally submitted to Mongol suzerainty. He sent his son, the future King Wonjong, to the Mongol court as a hostage. This ended the military resistance and made Goryeo a vassal state of the Mongol Empire.