The Cuthites were a people living in Samaria around 500 BC, and were to blame for the postponing of the 2nd temple, in the reign of Cyrus the Great. They did this after the Jewish people returned from Babylonian exile, and first agreed to help them, but after the Jews refused, they lied to king Cyrus who postponed the building process
The Cuthites are mentioned in Josephus, Antiquities Book 11, Chapter 4, as "Cutheans", naming them as those who were brought from Media and Persia and "planted" in Samaria by the King of Assyria after he had conquered the 10 tribes.