Dating the book of judges
They rejected Psalms because it was written (and collected from other Prophets) by King David.
They rejected Proverbs, Song of Songs, and Ecclesiastics, because those were written by King Solomon.
For this, the Samaritans developed a deep and terrible hatred for the Jews. They would send messages to the enemy overlord, claiming that the Jews were planning to revolt. They also built their own temple on Mount Gerizim, and there they worshiped an odd combination of religions, which includes their distorted version of the Chumash, and idolatry.
They began to worship Hashem, but it was soon discovered that they had not stopped worshiping their idols. The Jews could therefore not accept the Samaritans as Jews.
So all they kept were the Five Books of Moses, and Joshua.
The Book of Joshua tells of their capturing the land of Israel, so they felt it supported them.
When he took the Ten Tribes of Israel away from Samaria, he brought the people called the Cuthites to replace them. Since the Cuthites settled in the area known as Samaria (Shomron), they later became known as the Samaritans (Shomronim).
When the Cuthites were first relocated into Samaria, they were being killed by plagues of lions, and they did not know what to do about it.
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They rejected the Books of Samuel and Kings because those Books supported King David, and because they were written by the Prophets Samuel, Nathan, and Gad, who strongly supported King David.