Third king of the 18th Dynasty, successor to Amenhotep I. Soon after succeeding to the throne, he conducted a campaign against Nubia and succeeded in penetrating as far as the fifth cataract. A short time later, during an expedition to western Asia, he reached the far side of the river Euphrates. The areas through which he marched were not conquered, however. In northern Syria, Tuthmosis I was confronted by the kingdom of Mitanni, which became an important opponent of Egypt from then on. It is assumed that the expedition's main aim was to demonstrate Egypt's military power and to secure the trade routes for valuable goods. In Egypt itself, Tuthmosis began a huge building programme, including massive extensions and replacements to the temple of Karnak, founded in the Middle Kingdom. The mortuary temples and tombs of the kings were from now on separated from each other on the west bank at Thebes; the tombs lie hidden in the Valley of the Kings. Tuthmosis I's successor was not his oldest son (who died before his father) but a son by a minor wife, Tuthmosis II, who married Hatshepsut.