발해 건국을 도와 준 거란? 멸망 시킨 거란?

In 696, as the Tang Dynasty's Yingzhou region fell into chaos due to a Khitan rebellion, Dae Jo-yeong's forces seized the opportunity to escape and paved the way for the founding of Balhae. However, about 230 years later, the now-powerful Khitan invaded Balhae and destroyed it in 926. The Khitan rebellion that made the beginning of Balhae possible, and the Khitan that brought about Balhae's end...