Okonkwo committed these crimes that caused his exile:
1. he killed a man from his own tribe
2. he fought with his host
3 he did not apologize before running.
Step-by-step explanation:
Okonkwo is the titular character of the novel Things fall apart which deals with his life in a soon to be colonized Nigerian tribal village.
In the tribe that he lives, killing a person of the clan by will or without will is a sin that cannot go unpunished in their law.
He knows the rule however and quickly flees his town before anything would come up.