Xuantu Commandery
According to the Book of the Later Han, Buyeo was in close diplomatic relations with the Xuantu Commandery, one of Four Commanderies of Han in the later Western Han. Buyeo entered into formal diplomatic relations with the Eastern Han dynasty by the mid-1st century AD as an important ally of that empire to check the Xianbei and Goguryeo threats. Buyeo was then reclassified as part of Liaodong Commandery of the Eastern Han. After an incapacitating Xianbei invasion in 285, Buyeo was restored with help from the Jin dynasty. This, however, marked the beginning of a period of decline. A second Xianbei invasion in 346 finally destroyed the state, except some remnants in its core region which survived as vassals of Goguryeo until their final annexation in 494.