Genghis khan i think
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Answer:
Native Americans suffered 80-90% population losses in most of America with influenza, typhoid, measles and smallpox taking the greatest toll in devastating epidemics that were compounded by the significant loss of leadership.
Explanation:
1. Difficult during the winter.
2. Can't sail back.
3. Bad weather conditions.
I would type more but I can't see the rest