Upon ascending to the throne, King Micheon focused on expanding his country’s territory. He was able to broaden Goguryeo’s borders into the Liaodong Peninsula and other Chinese commanderies. Meanwhile, across from Goguryeo in China, the Jin Dynasty was losing power and was about to disintegrate. King Micheon did not miss this opportunity. In the year 302, he led 30,000 troops himself and attacked Xuantu, one of the Jin Dynasty’s commanderies. He captured 8,000 people and took them to Goguryeo. That was the king’s first military campaign, which turned out to be a success.

The king continued to develop the Goguryeo army into a powerful force. He annexed the Lelang and Daifang commanderies in 313 and 314, respectively. As a result, Goguryeo was able to take economic benefits that the two commanderies had previously enjoyed from intermediary trade between the Jin Dynasty and other eastern states. At the time, it was common for Goguryeo people to use cows and farming tools made of iron when doing farm work. They were able to reap a good harvest in the new, fertile lands of the two commanderies. This provided Goguryeo with an important base for economic development.

More importantly, after the two military campaigns, Goguryeo successfully expelled Chinese forces from the Korean Peninsula, ending nearly 400 years of Chinese presence on the Peninsula. From then on, no other Chinese dynasties would occupy land there again.

In China, tribes and smaller states began to establish their own kingdoms, signaling the chaotic period of Five Dynasties and Sixteen Kingdoms. Taking advantage of the confusion in China, King Micheon attempted to expand Goguryeo’s territory even further. But Goguryeo was interrupted by Xianbei forces in the west. A tribe called Murong Bu, in particular, proved to be a major threat. King Micheon even allied with other Xianbei tribes to defeat Murong Bu, only to fail. Throughout King Micheon’s period in the early 4th century, Goguryeo and Murong Bu engaged in fierce battles in Liaodong, but neither side secured a solid victory. Unfortunately, King Micheon’s attempt to advance further into the west was thwarted in the end.

From a poor boy who spent his youth selling salt and keeping frogs away, King Micheon was able to change his fate and his kingdom’s borders as well. Having experienced the harsh realities of ordinary people, the king tried hard to improve public livelihood. During his reign, agriculture and commerce in Goguryeo grew rapidly, with its territory expanded significantly. It would be fair to say that the king laid the foundation for the kingdom to make remarkable developments in the coming decades—the period of his great-grandson, King Gwanggaeto the Great.

King Micheon died in the year 331 and was buried in a place called Micheon, meaning the Beautiful Stream. His posthumous name came from this burial site.