The people, who became known as the Samaritans, came from the Assyrian empire. When the ten tribes of Israel were taken captive by Assyria, the Assyrians sent foreign people to populate the land. 

2 Kings 17:23-34,”So the people of Israel were taken from their homeland into exile in Assyria, and they are still there. The king of Assyria brought people from Babylon, Kuthah, Avva, Hamath and Sepharvaim and settled them in the towns of Samaria to replace the Israelites. They took over Samaria and lived in its towns. When they first lived there, they did not worship the LORD; so he sent lions among them and they killed some of the people. It was reported to the king of Assyria: ‘The people you deported and resettled in the towns of Samaria do not know what the god of that country requires. He has sent lions among them, which are killing them off, because the people do not know what he requires.’ Then the king of Assyria gave this order: ‘Have one of the priests you took captive from Samaria go back to live there and teach the people what the god of the land requires.’ So one of the priests who had been exiled from Samaria came to live in Bethel and taught them how to worship the LORD. Nevertheless, each national group made its own gods in the several towns where they settled, and set them up in the shrines the people of Samaria had made at the high places…They worshiped the LORD, but they also served their own gods in accordance with the customs of the nations from which they had been brought. To this day they persist in their former practices.”

Please recognize, God did not make a covenant with the Samaritans; but He did respect their attempts to follow His Law. Whereas, God is still in covenant relationship with the Jews. 

Recall Jesus’ experience with the Samaritan woman. John 4:9 (ESV), “The Samaritan woman said to him, “How is it that you, a Jew, ask for a drink from me, a woman of Samaria?” (For Jews have no dealings with Samaritans.)” Jesus responded (John 4:22-24 ESV), “You worship what you do not know; we worship what we know, for salvation is from the Jews. But the hour is coming, and is now here, when the true worshipers will worship the Father in spirit and truth, for the Father is seeking such people to worship him. God is spirit, and those who worship him must worship in spirit and truth.”