Was it simply too long a march for an army? Mongols managed to make it all the way to Eastern Europe and the Middle East, so I don't see any reason why they can't just march or ride around the western edge of the Great Wall. They also had naval capabilities (as shown during the Mongol invasions of Japan), so couldn't they have departed by ship off the coast of Northeastern China or Eastern Russia and to land anywhere south of the Wall's eastern end?

只是簡單地因為這個路線對于軍隊來說行軍時間太長了嗎?蒙古人成功地打到了東歐和中東,所以我看不出他們為什么不能沿著長城的西端行進。他們還具有海軍能力(如在蒙古入侵日本期間所顯示的那樣),那么他們難道不可以乘船離開中國東北沿?;蚨砹_斯東部沿海,并登陸到長城東端以南的任何地方嗎?