The Koguryo Kingdom of Korea

Koguryo, a shortened form of Goguryeo, was adopted as the official name in the 5th century and is the source of the English name “Korea.” Goguryeo, was a Korean kingdom that spanned the northern and central Korean Peninsula as well as the southern and central parts of Northeast China. Goguryeo ruled over most of the Korean peninsula, large parts of Manchuria, and parts of eastern and Inner Mongolia at its peak.

It is the largest of the three kingdoms that divided ancient Korea until 668BC. Koguryo is traditionally said to have been founded in the Tongge River basin of northern Korea around 37BC by Chu-mong, leader of one of the area’s Puy tribes, but modern historians believe the tribal state was formed in the 2nd century BCE. Korea’s rich history and culture encompass many aspects including the history of the Korean language which is a pivotal factor of the Korean civilization. 

The Root of Koguryo Kingdom

The name Goguryeo can be traced back to 113 BC, when Emperor Wu of Han China conquered Gojoseon and established the Four Commanderies, in the name of Gaogouli County, Xuantu Commandery. Beckwith, on the other hand, claimed that the record was incorrect. Instead, he proposed that the Guguryeo people originated in or near Liaoxi, western Liaoning, and parts of Inner Mongolia before migrating eastward, citing another account in the Book of Han. The early Goguryeo tribes were administered by the Xuantu Commandery and were regarded as reliable clients or allies by the Han. 

The most prominent Goguryeo leaders were given Han rank and status, with the Marquis of Goguryeo wielding relatively independent authority within Xuantu. Some historians attribute greater power to the Goguryeo during this period, tying their insurgency to the fall of the first Xuantu Commandery in 75 BC. Emperor Taizong mentions Goguryeo’s history as being around 900 years old in the Old Book of Tang (945). According to the 12th-century Samguk sagi and the 13th-century Samgungnyusa, after a power struggle with other princes of the court, a prince from the Buyeo kingdom named Jumong fled and founded Goguryeo in 37 BC in a region called Jolbon Buyeo, which is usually thought to be in the middle Yalu and Tongjia Rivers basin, which straddles the current China-North Korea border.

The Centralization and the Early Expansion

Goguryeo arose from a league of various Yemaek tribes and quickly expanded its power from its original basin of control in the Hun River drainage. Five local tribes were reorganized into five centrally ruled districts during Taejodae’s reign in 53 AD. The king oversaw foreign relations and the military. Early expansion may be best explained by ecology; Goguryeo ruled over territory in what is now central and southern Manchuria and northern Korea, both of which are mountainous and devoid of arable land. Following historical pastoralist tendencies, Goguryeo may have been unable to harness enough resources from the region to feed its population after centralizing, and thus sought to raid and exploit neighboring societies for their land as well as resources.

Taejo conquered the Okjeo tribes of northeastern Korea, as well as the Dongye and other tribes in Southeastern Manchuria and Northern Korea. Taejodae led Goguryeo in an attack on the Han Commanderies of Lelang and Xuantu in the Korean and Liaodong Peninsulas, allowing them to become fully independent. Taejodae allowed conquered tribes to keep their chieftains, but they had to report to governors related to Goguryeo’s royal line; tribes under Goguryeo’s jurisdiction were expected to pay heavy tribute. Taejodae and his successors used the additional resources to continue Goguryeo’s north and westward expansion.

The expanding Goguryeo kingdom quickly made direct military contact with the Liaodong Commandery to the west. Under Liaodong’s pressure, Goguryeo relocated their capital from the Hun River valley to the Yalu River valley near Hwando.

The Goguryeo–Wei Wars

Following the fall of the Han Dynasty, the former Han commanderies had become independent and were ruled by various warlords. Surrounded by these commanderies, which were ruled by aggressive warlords, Goguryeo sought to improve relations with China’s newly formed Cao Wei dynasty and sent tribute in 220. Goguryeo formed a formal alliance with Wei in 238 to destroy the Liaodong commandery.

When Wei finally conquered Liaodong, cooperation between Wei and Goguryeo broke down, and Goguryeo attacked the western edges of Liaodong, prompting a Wei counterattack in 244. Thus, in 242, Goguryeo launched the Goguryeo–Wei War, attempting to cut off Chinese access to its territories in Korea by seizing a Chinese fort. The Wei state, on the other hand, responded by invading and defeating Goguryeo. In 244, Wei forces destroyed Hwando’s capital. Dongcheon is said to have fled to the eastern state of Okjeo after his army was destroyed. According to the Samguk sagi, Jungcheon assembled 5,000 elite cavalries and defeated the invading Wei troops, beheading 8,000 enemies.

The Goguryeo Revival and further Expansion

In about 70 years, Goguryeo rebuilt its capital Hwando and resumed raids on the commandaries of Liaodong, Lelang, and Xuantu. As Goguryeo expanded its reach into the Liaodong Peninsula, Micheon conquered and absorbed the last Chinese commandery at Lelang in 313, bringing the remaining northern part of the Korean peninsula into the fold. This conquest marked the end of Chinese rule over the northern Korean peninsula, which had lasted 400 years. From then until the 7th century, territorial control of the peninsula was primarily contested by the Three Kingdoms of Korea.

Goguryeo’s Epitome of Power 

Under Gwanggaeto the Great and his son Jangsu, Goguryeo experienced a golden age. Goguryeo territories included three-quarters of the Korean Peninsula, including what is now Seoul, almost all of Manchuria, and parts of inner Mongolia during this period. Based on the discovery of Goguryeo fortress ruins in Mongolia, there is archaeological evidence that Goguryeo’s maximum extent lay even further west in present-day Mongolia.

Gwanggaeto the Great (391–412) was a vigorous emperor known for his rapid military expansion of the realm. He established the era name Yeongnak, or Eternal Rejoicing, establishing Goguryeo on equal footing with the Chinese mainland dynasties. During his campaigns, Gwanggaeto conquered 64 walled cities and 1,400 villages. Gwanggaeto achieved undisputed control of the majority of Manchuria and more than two-thirds of the Korean Peninsula. Gwanggaeto’s exploits were memorialized on a massive memorial stele erected by his son Jangsu in present-day Ji’an, on the Chinese-North Korean border.

The Decline of Power

Goguryeo was at its peak in the sixth century. However, it then began a steady decline. Anjang was assassinated and was succeeded by his brother Anwon, whose reign saw an increase in aristocratic factionalism. A political schism widened as two factions pushed for different princes to succeed until the eight-year-old Yang-won was crowned. However, the power struggle was never definitively resolved, as renegade magistrates with private armies appointed themselves de facto rulers of their domains.

Taking advantage of Goguryeo’s internal conflict, a nomadic group known as the Tuchueh attacked and conquered some of Goguryeo’s northern lands in the 550s. As civil war raged among feudal lords over royal succession, Baekje and Silla joined forces to attack Goguryeo from the south in 551.

The Conflicts of the late 6th and 7th centuries

Goguryeo was frequently at odds with China’s Sui and Tang dynasties in the late 6th and early 7th centuries. It had complicated relationships with Baekje and Silla, alternating between alliances and enmity. The Eastern Göktürk, a nominal ally of Goguryeo, was a neighbor in the northwest. Baekje and Silla formed an alliance in 551 AD to attack Goguryeo and conquer the Han River valley, a strategic location near the peninsula’s center and a fertile agricultural region. Silla troops arrived on the pretext of helping and attacked and took possession of the entire Han River valley in 553 after Baekje had exhausted themselves with a series of costly assaults on Goguryeo fortifications.

The expansion of Goguryeo clashed with Sui China, escalating tensions. Goguryeo launched a preemptive attack on Liaoxi in 598, prompting Emperor Wen to launch a land and sea counterattack, which ended in disaster for Sui. Sui’s most disastrous campaign against Goguryeo occurred in 612, when he mobilized 30 division armies, or about 1,133,800 combat troops, according to the Sui Dynasty’s History. A detachment of nine division armies, totaling about 305,000 troops, pinned along Goguryeo’s line of fortifications on the Liao River, bypassed the main defensive lines, and headed towards Pyongyang, the Goguryeo capital, to link up with Sui naval forces, who had reinforcements and supplies.

Goguryeo’s Fall

When Yeon Gaesomun died of natural causes in the summer of 666, Goguryeo was thrown into chaos and weakened by a succession battle between his sons and younger brother. His oldest son Yeon Namsaeng succeeded him as Dae Mangniji, the highest position newly created during the reign of Yeon Gaesomun. The Chinese army crossed the Liao River in 667 and took Shin/Xin Fortress (modern-day Fushun, Liaoning). After repelling Yeon Namgeon’s counterattacks, the Tang forces joined forces with the defector Yeon Namsaeng and received all possible assistance from him, despite being unable to cross the Yalu River due to resistance.

While Yeon Namgeon fought on in the inner city, his general, the Buddhist monk Shin Seong, turned against him and surrendered the city to Tang forces. Yeon Namgeon attempted suicide but was apprehended and treated. This was the end of Goguryeo, and Tang annexed it into its territory, with Xue Rengui serving as protector general over the former Goguryeo territory.

Revival movements

Many Goguryeo people rebelled against the Tang and Silla after the fall of Goguryeo in 668 by founding Goguryeo revival movements. Geom Mojam, Dae Jung-sang, and several well-known generals were among them. The Tang Dynasty attempted but failed to establish several commanderies to rule over the region.

Tang crowned Bojang “King of Joseon” in 677 and assigned him command of the Protectorate General to Pacify the East’s Liaodong commandery. To revive Goguryeo, Bojang continued to foment rebellions against Tang, organizing Goguryeo refugees and allying with the Mohe tribes. In 681, he was exiled to Sichuan, where he died the following year. 

There is a long line and rich history of rising and falling to power before Korea reached where it is today. The varied history of the Korean royal family as well as the persistent developments of the Korean era shaped so much of the diverse yet indwelling psyche and temperament of its people.