gwern, I amended my coment (grandparent of this comment) so that now our comments no longer contradict each other. For those reading via the comment feed, here is gwern's comment again:

Correct me if I'm wrong, but my history books make a specific point of mentioning that Mongol treatment of captured cities was incredibly brutal when the city had resisted, and that cities that immediately surrendered were treated very well; which is what taw is saying with 'just giving in'.