Baoyi Qaghan vs King Chungnyeol of Goryeo

Baoyi Qaghan ascended to the throne of the Uyghur Khaganate after the death of his father, Tun Bagha Tarkhan. His reign continued the policies of his father, maintaining stability and alliance with Tang.

Baoyi Qaghan married a Tang princess, Princess Xian'an, as part of a diplomatic alliance. This marriage strengthened ties between the Uyghur Khaganate and Tang China, ensuring peace and trade.

Baoyi Qaghan led campaigns against the Yenisei Kyrgyz, who were threatening Uyghur northern borders. The Uyghur forces defeated the Kyrgyz, securing the khaganate's northern frontier.

Baoyi Qaghan died in 821, succeeded by his son Chongde Qaghan. His reign was marked by continued prosperity and strong relations with Tang China.

King Chungnyeol provided Goryeo ships, troops, and supplies for the first Mongol invasion of Japan. Goryeo forces suffered heavy losses in the failed campaign, which ended with the destruction of the fleet by a typhoon. This strained Goryeo's resources and population.

King Chungnyeol married Princess Jeguk, a daughter of Kublai Khan, becoming the first Goryeo king to take a Mongol wife. This marriage formalized the Mongol-Goryeo alliance and made Chungnyeol a Mongol son-in-law (kuregen), strengthening ties with the Yuan dynasty.

King Chungnyeol ordered Goryeo officials to adopt Mongol hairstyles and clothing, and introduced Mongol court ceremonies. This policy aimed to appease the Yuan court but caused resentment among Korean nobles who saw it as a betrayal of Korean identity.

King Chungnyeol again mobilized Goryeo's navy and army for the second Mongol invasion of Japan. The campaign ended in disaster when a typhoon (kamikaze) destroyed the combined Mongol-Goryeo fleet, resulting in massive casualties and further draining Goryeo's economy.