[bleep]ing ridiculous. In a camp of over 100,000, in the middle of enemy territory, - with night watchmen posted as you said - ALL but 10,000 of them were asleep. Nor did they have their weapons by them. Nor their clothes. Nor were they even trained, they made breakfast while the mongols rained [cabbage] down on them. The [bleep]? If you're on the march you don't sleep for 8 hours, and with scouts scouring the area Mongols don't just suddenly show up with huge siege engines in a matter of minutes.