Samaria is a place name in Israel, and it was the capital of the Northern Kingdom of Israel which was divided after Solomon's death. During the time of Ahab and Jezebel, it enjoyed its greatest military and economic prosperity, but it fell along with the destruction of the Northern Kingdom of Israel by the Assyrian Empire.
Before the unified kingdom, it was a region called Shechem, located between Mount Gerizim and Mount Ebal. Currently, it is an autonomous region of the Palestinian Liberation Organization.
The Assyrian Empire actively pursued a policy of intermarriage to maintain the homogeneity of the empire, and the Israelites who were taken to Babylon lost their ethnic unity during their captivity.
Although they returned after the Babylonian captivity, the descendants of the Southern Kingdom of Judah did not recognize the Samaritans as their own people, and when traveling from the south to Galilee in the north, they would bypass Samaria by going around the Jordan River.
The Samaritans, leaving the Jews who despised them, built a separate temple on Mount Gerizim and offer sacrifices there.