Northeast Asian History Network

Although a variety of industries thrived in Koguryo, the emphasis was on agriculture. However, agricultural productivity was not high in the middle Yalu River basin. The records indicate that the food supply was inadequate despite the Koguryo people’s best efforts. Thus, hunting and breeding of livestock were also prevalent in Koguryo. In addition, insufficient materials were secured through warfare and plunder; however, plundering was not always successful. Warfare for the sole purpose of plundering sometimes ended in failure, or there was nothing to pillage even when the armies were victorious. Plundering proved to be an unreliable method for securing goods. Rather than continue to engage in warfare for plundering, Koguryo began annexing surrounding regions for a sustainable supply of goods under the guidance of King Taejo of Koguryo^{[note 001]} from the mid-first century. Thus began Koguryo’s tributary relations with annexed regions.
Koguryo began full-scale territorial expansion centered in the middle Yalu River basin. Until the third century, Koguryo annexed Okjeo^{[note 002]} and Eastern Ye^{[note 003]} in the east, Yangmaek^{[note 004]} in the west, and Sushen^{[note 005]} in the north. Koguryo allowed autonomy in its annexes and in turn received tributes on a regular basis. Koguryo received a variety of specialty goods in addition to agricultural supplies. Okjeo delivered salt and various seafoods. As the number of subordinate states grew, a vast amount of materials were gathered in Gungnae Fortress^{[note 006]}, the capital of Koguryo. Naturally, Koguryo's ruling class, the Jega, wished to increase the economic wealth by annexing an even wider area. The desire for conquests had thus increased.
To make conquests, it was necessary for Koguryo to maintain the country's political structure. So, Koguryo focused its political system around the king.
As indicated in the above excerpt, different levels of official ranks were placed under the king. As recorded in the "History of the Three Kingdoms," various official positions were created including Daebo (Great Minister), Jwabo (Minister of the Left), Woobo (Minister of the Right), Guksang (National Secretary), and Jungwedaebu (Minister of the Interior and Exterior). ‘Gwandeung’ were ranks of court officials, and ‘Gwanjik’ were their official positions. The king granted official ranks and official positions to the ruling class including the Jega and commanded them under the kingship as his court officials. In addition, the king collected taxes through said officials and provided a more stable form of government. Furthermore, a five-unit system was devised to maintain this stable government.
Under the rule of King Gogukcheon of Koguryo (reign: 179-197 CE), in the late 2nd century, Koguryo's five government branches ^{[note 007]} were referred to as the Northern, Eastern, Western, Southern, and Central branches. Gungnae Fortress was the central administrative region. The five branches of Jega gradually moved toward the central administrative region over the course of three centuries. The five-branch ruling class eventually transformed into the central nobility. Thus, Koguryo's distributed state powers became concentrated in the center, and the centralization process was in full swing.
As the central administrative region was being formed, cities, townships, and villages were being installed in the surrounding areas. Local government officials were dispatched to each administrative unit. Local government officials, appointed by the king, had direct rule of their respective regions. Local government offices were installed in main points on the roads leading to Gungnae Fortress. Eventually, local government officials were dispatched even to annexed areas such as Okjeo and Eastern Ye. By the 4th century, Koguryo fully ruled its surrounding regions through local government offices.