They also made Mt. Gerizim near Schechem the center of their religion as opposed to Mr. Moriah in Jerusalem. http://www.the-samaritans.com/
In the Bible, it says that the Samaritans are descended primarily from colonists whom the Assyrians transported into Israel after they destroyed Samaria. As with the Babylonians later the Assyrians did not deport every Jew from the land. Just the young, strong, useful, skilled, educated, and presumably hot. The lowest classes were left behind. These presumably mixed with the exiles the Assyrians transported in.
But as we see in the New Testament the Judeans considered them asterisk Jews.