The true founder of the Hittite Empire was Suppiluliuma I (r. ca. 1344–1322 BCE). Although the order of events is not clear, it is probable that this monarch took the throne by murdering his brother Tudhaliya III. During the reign of his father (Tudhaliya II), Suppiluliuma participated in a failed expedition against Mitanni, a powerful Hurrian state centered in Syria. It is clear that Suppiluliuma reestablished Hittite power in Anatolia. Furthermore, he made the kingdom of Mittani and other kingdoms in Syria (e.g., Nuhashshe, Amurru, and Ugarit) subordinate to the Hittites. He also required the conquered kingdoms to sign long-lasting loyalty treaties with the Hittite royal house. Many of these treaties have been excavated and published.