The people of the West Bank have engaged in terrorism against Israeli civilians up to 2005 - https://en.wikipedia.org/wiki/Second_Intifada - and that's not particularly ancient history.
9/11 didn't happen out of the blue, it was a response to american foreign policy in the middle east.
The troubles didn't happen because the IRA thought British rule was legitimate
Etc.
The vast majority of terrorism is because one group is controlling a region that the other group thinks they should not.
In my opinion, most long running conflicts tend to have both sides doing terrible things over the course of the conflict, so its rare there is one side that is "good" and one that is "evil".
I know, that's exactly what England did under Cromwell; one of my ancestors was such a settler.