It began when the nation Israel was divided into the northern kingdom and the southern kingdom. The capital of the northern kingdom was Samaria, while that of the south was Jerusalem. The king of the north, established a rival center of worship in Samaria. And that started it all.
It became worse when the northern tribes intermarried with Gentiles during the Assyrian invasion. The southern tribes viewed those who intermarried in the north as half-dogs.
It became worst when the Samaritans gave the returning Jews trouble in rebuilding Jerusalem during the time of Nehemiah.
