Why was the kingdom divided in the Old Testament?


"But King Solomon loved many foreign women, as well as the daughter of Pharaoh: women of the Moabites, Ammonites, Edomites, Sidonians, and Hittites- from the nations of whom the LORD had said to the children of Israel, "You shall not intermarry with them, nor they with you. Surely they will turn away your hearts after their gods." Solomon clung to these in love. And he had seven hundred wives, princesses, and three hundred concubines; and his wives turned away his heart. For it was so, when Solomon was old, that his wives turned his heart after other gods; and his heart was not loyal to the LORD his God, as was the heart of his father David. For Solomon went after Ashtoreth the goddess of the Sidonians, and after Milcom the abomination of the Ammonites. Solomon did evil in the sight of the LORD, and did not fully follow the LORD, as did his father David. Then Solomon built a high place for Chemosh the abomination of Moab, on the hill that is east of Jerusalem, and for Molech the abomination of the people of Ammon. And he did likewise for all his foreign wives, who burned incense and sacrificed to their gods. So the LORD became angry with Solomon, because his heart had turned from the LORD God of Israel, who had appeared to him twice, and had commanded him concerning this thing, that he should not go after other gods; but he did not keep what the LORD had commanded. Therefore the LORD said to Solomon, "Because you have done this, and have not kept My covenant and My statutes, which I have commanded you, I will surely tear the kingdom away from you and give it to your servant. "Nevertheless I will not do it in your days, for the sake of your father David; I will tear it out of the hand of your son. "However I will not tear away the whole kingdom; I will give one tribe to your son for the sake of my servant David, and for the sake of Jerusalem which I have chosen"" (1 Kings 11:1-13)