Okjeo was Korean tribal state which arose in the northern Korean peninsula from perhaps 2nd century BCE to 5th century CE.
Dong-okjeo (Eastern Okjeo) occupied roughly the area of the Hamgyŏng provinces of North Korea, and Buk-okjeo (Northern Okjeo) occupied the Duman River region.
Dong-okjeo was often simply called Okjeo, while Buk-okjeo was also sometimes referred to as Chiguru (置溝婁, 치구루) or Guru (구루), the latter name being also applied to Goguryeo. Okjeo bordered the other minor state of Dongye on the south, and shared a similar fate.
In its early history, Okjeo oscillated between domination by the Chinese commanderies and by Goguryeo. From the 3rd century BCE to 108 BCE, it was controlled by Gojoseon due to the constant interference of its neighbors, Okjeo never grew into a fully centralized kingdom. In 28 BC, King Dongmyeong sent Bu Wiyeom to attack the Northern Okjeo. In the 1st or 2nd century CE, King Taejo of Goguryeo reduced Okjeo to a tributary, which delivered local products to Goguryeo. During the 244 Wei Invasion of Goguryeo, Goguryeo’s King Dongcheon briefly retreated to North Okjeo, and in 285, the Buyeo court also temporarily escaped to Okjeo under northern nomadic attacks.
Our knowledge of Okjeo culture is fragmentary. As with the Dongye and Okjeo's language, food, clothing, architecture, and customs were similar to that of Goguryeo. The Okjeo people practiced arranged marriage by which the child-bride lived with the child-groom's family until adulthood, and they interred the dead of a family in a single coffin.