PS: The new book 'Recasting Rivers and Mountains' has been uploaded, please support me. The famous history professor Li Jun came to the turbulent era of the Southern Song Dynasty due to an accidental air crash, and unfortunately he became the subjugated emperor Song Du Zong became the opponent of the mighty Kublai Khan, and what's worse, Boyan's army had already approached the city of Lin'an. In the critical autumn of the Southern Song Dynasty, when internal and external troubles occurred, how would Li Jun choose? Can the survival of the Southern Song Dynasty be restored?