Jupiter, also Jove (Latin:Iuppiter [ˈjʊppɪtɛr], gen. Iovis [ˈjɔwɪs]), is the god of sky and thunder and king of the gods in Ancient Roman religion and mythology. Jupiter was the chief deity of Roman state religion throughout the Republican and Imperial eras, until Christianity became the dominant religion of the Empire. In Roman mythology, he negotiates with Numa Pompilius, the second king of Rome, to establish principles of Roman religion such as sacrifice.