The Samaritans are of the people of Israel. They just belong to different tribes than Judah. As such, their religion, while based on the Hebrew bible just like Judaism is, has some differences. They do not believe in the Rabbinical authorities or the 'halacha' (the oral Tora), which is understandable as these were developed specifically by the Jews, the people of the tribe of Judah. They also view mount Gerizim as the holy of holies rather than Jerusalem, which again is understandable. Jerusalem, after all, was the capital of Judea, not the ancient Israel after the separation of the kingdoms. So the significance of Jerusalem was always major for Jews, but not necessarily for other children of Israel. Nevertheless, they are considered our distant brothers and sisters, and some important Rabbis have said they should be considered fully Jewish or half Jewish. They used to be a big population, hundreds of thousands, maybe more. But failed rebellion attempts and persecution dropped their numbers to just a few hundreds these days. The ancient Samaritan structure that was discovered underneath the Arab village Qassim is more evidence that in this land it is us - the Jews, the Samaritans, the children of Israel - who are the natives, and it is the Arabs who are the colonisers.