The Battle of Cheonmun-ryeong, also known as the Battle of Tianmenling, is a battle fought between Dae Jo-yeong, later founder of Balhae, and Li Kaigu, a Khitan commander of the Chinese Tang Dynasty.
“Hegel remarks somewhere that all great, world-historical facts and personages occur, as it were, twice. He has forgotten to add: the first time as tragedy, the second as farce”