Muhammad sent his cousin Ali to Sana'a and its surroundings around 630 CE. At the time, Yemen was the most advanced region in Arabia. The Banu Hamdan confederation was among the first to accept Islam, second only to the Somalis, Afar and Habesha. Muhammad sent Muadh ibn Jabal, as well to Al-Janad, in present-day Taiz, and dispatched letters to various tribal leaders. The reason behind this was the division among the tribes and the absence of a strong central authority in Yemen during the days of the prophet.