The Middle Kingdom crumbled in the Second Intermediate Period (c. 1650–1550 BC), but the country was again reunited by Theban rulers, who became the first pharaohs of the New Kingdom. Under the new regime, Amun became the supreme state god. He was syncretized with Ra, the long-established patron of kingship and his temple at Karnak in Thebes became Egypt's most important religious center. Amun's elevation was partly due to the great importance of Thebes, but it was also due to the increasingly professional priesthood. Their sophisticated theological discussion produced detailed descriptions of Amun's universal power.