Samuel said to him, Yahweh has torn the kingdom of Israel from you this day, and has given it to a neighbor of yours who is better than you.
Most scholars are sure Saul attacked the Amalekites who lived in the southern Judah Negev, though some feel he attacked an enclave of them in western Samaria. [Note: E.g., Diane Edelmann, "Saul’s Battle Against Amaleq (1 Samuel 15)," Journal for the Study of the Old Testament 35 (June 1986):74-81.] Saul did not destroy all the Amalekites at this time (1 Samuel 27:8; 1 Samuel 30:1; 2 Samuel 8:12). King Hezekiah completely annihilated them years later (1 Chronicles 4:43).