Or so I've read, from people smarter than me (which is everybody).
The residents of Judea and Samaria never got along. Mostly because of - SURPRISE! - religion. They worshipped similar monotheistic but different gods. The Samaritans had their own god, scriptures, holy mountain, etc. etc.
The Sunday School story of the "Good Samaritan" started as a way for the Samaritans to poke fun at their neighbors: "Look at those self-righteous, stiff-necked Jews! One of their own lies bleeding in a ditch and they won't even stop to help him. Only one of us helped!"
And like many such stories, it was eventually co-opted by the other side to make them look better.
There was one recorded incident when the Jews and Samaritans worked together, according to Isaac Asimov's "Guide to the Bible." They were jointly ruled by the son of Herod the Great, Herod Archelaus, who seems to have been a major screw-up on an epic, G.W. Bush scale. The two groups formed a joint committee and complained to the Roman governor in Syria. The Romans must have agreed. They not only removed Archelaus from office, they sent him as far away from Palestine as possible - to the Roman outpost in the city known today as Vienna, Austria.
Long as I'm here - according to Flavius Josephus, the one Messiah who directly challenged Roman authority came from Samaria, not Nazareth. Sometime after Alleged Jesus was executed, a Samaritan Messiah gathered a huge mob and marched it to the Samaritan holy mountain, while preaching about removing the Romans from the area etc.
This episode ended the usual way - Pontius Pilate held a trial, found the Messiah innocent, then got scared of the mob, reversed himself and had the prisoner crucified. Just kidding! Pilate promptly sent in his troops, killed a bunch of the insurgents, captured their Messiah and executed him.
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