What is "balhae"

Balhae was a medieval kingdom of the Goguryeo and Mohe peoples in the northern Korean Peninsula and southeastern Manchuria. It existed during Korea's North–South States Period along with Later Silla.

Balhae was established under the name Jin by King Go in 698 after his defeat of the Tang Empire at Tianmenling. It eventually occupied areas within present-day northern Korea, areas of China's Northeast, and Russia's Maritime Province. It was defeated by the Khitans in 926. Most of its northern territories were absorbed into their Liao dynasty, while the southern parts were absorbed into Goryeo.