There were actually six influential kingdoms during this era many of which dominated during different periods of the era.

Kaya

This confederation of six Pyon-Han tribes is the often overlooked. Smaller than than the rest, they actually maintained good relations with the Japanese. Located in extreme southern Korea, many of their relatives had migrated to Japan. At this time the Japanese actually maintained a military garrison in Kaya-Korea. Paekche often used them as a buffer with Silla. However once Silla became powerful, they destroyed the Kaya League.

Koguryo

This was the dominate kingdom in northern Korea with an active military history. They had conflicts with their Chinese neighbors, marauding nomadic tribes from Mongolia/ Manchuria, and their southern relatives. The conflicts with their southern neighbors focused on control of the Han River valley. At their height of power, they controlled two-thirds of modern Korea and across the Yalu into Southern Manchuria near the Liao River. The kingdom was established around 18BC and was dominated by a merger of Koguryo and five migratory Puyo tribes. They were both allies and opponents of the Nangnang colony until they finally absorbed it in 313 AD.

Though they often paid tribute to the dominate Chinese power in North China, they lead uprisings and fought several serious wars with the Chinese. In the campaigns of 240's AD and 340's AD their capital was destroyed by Chinese forces. They continued to fight their southern neighbors in the Han River Valley. They established an alliance with the Silla to fight their common enemy the Paekche. Soon the balance of power shifted and a new Paekche-Silla alliance wrested control of the disputed area from the Koguryo. Even after this set back, Koguryo was powerful enough to repel several Tang Dynasty invasions. Finally a Tang-Silla alliance was able to defeat them by 668.

Paekche

Located in the southwestern section of the peninsula, it was controlled by fifty MA-Han tribes with a few Puyo immigrants. It was dominated by a feudal form of government. The feudalism was reflected in the military by each local leader bringing a personally loyal force to any nationally raised muster. Though they often fought the Silla, their main enemy was Koguryo. Because of this , at different times they maintained alliances with both the Silla and Japan. Twice because of pressure from Koguryo, they moved their capital further south. They would be crushed by a joint TANG China and Silla invasion in 663.

Later-Paekche (Neo-Paekche)

Centered around Paekche families in Southwest Korea in 890. A Silla force crushed the revolt.

Silla

This kingdom grew out of a confederation of tweleve Chin-Han tribes located south of the han River in the eastern region of the peninsula. During the early years they were allied with the Koguryo and fought a stalemate war with the Paekche. This security allowed them to strengthen. When they did go on the offensive, they quickly destroyed the Kaya Confederation and grabbed land from the Paekche. Then with Paekche as an ally they began to fight with the Koguryo over control of the Han River. The Paekche alliance did not last long because as soon as the Han river valley was secure, the Silla launched a consoldating campaign against their former ally.

By AD, they contoled two-thirds of southern Korea and in an alliance with Tang China, they were able to destroy the Koguryo Dynasty. Next in a remarkable feat of diplomatic fervor, the Silla was able to unite the defeated Paekche and Koguryo forces into a united army with which they prevented Tang China from colonizing Korea again. The Silla dynasty fought several wars with northern maurading nomadic tribes and several weak Chinese invasions. They destroyed a Neo-Paekche kingdom in 892 . A weak monarchy resulted in numerous private armies loyal only to specific nobles. This resulted in numerous peasant revolts and a lengthy civil war. As a result a Neo-Koguryo kingdom called Koryo succeded in replacing the Silla monarchy in 901.

Parhae

A large empire carved from the part of Koguryo annexed by TANG China. It extended far north and south of the Yalu and Tumen rivers and maintained five capitals. Though initially supported by the TANG as a buffer state with the wild nomadic northern Manchuria, the Parhae semi-independent nature lead to several conflicts between the two countries.

Koryo

This dynasty has also been referred to as 'Later Koguryo" and 'Neo-Koguryo' due to the location of their rise to power, northern Korea, and the ethnic background of its rulers. After 770, Korea was turbulent with peasant revolts and civil wars between the important families and their private armies. The Koryo leaders were from one of these forces and replaced the ruling Silla factions by 918. A Unification war was conducted against other families until 935. They also fought several wars with powerful nomadic tribes which were invading Northern China at the same time.

After suffering intial defeats the Koryo would shift their tribute payment to the new dominate non-Chinese power in Northern China. First it was the Khitan/Liao, 993-1018, then the Jurchen ,1104-1115, and finally the Mongols, 1231. The Mongol era of control was filled with guerrilla warfare against the Mongols but the Koreans did contribute 1000s of troops for the ill-fated Mongol invasion of Japan. Koryo with little real power lasted until one its own Generals , Yi-Song-Gye, lead a revolt which replced the weak Koryo king in 1388.

More Ancient Korea

Military History Through the Three Kingdoms Era
Era of the Three Kingdoms
Chronology of Ancient Korean Military History
Summary of Ancient Korean Kingdoms
Armies of Korea: Organization until 1388
Armies of Ancient Korea: Uniforms Until 1388
DBA/DBM Variants