The Lakhmids were a group of Arab Christians. The Lakhmid Kingdom was founded by the Lakhum tribe that emigrated from Yemen in the 2nd century and ruled by the Banu Lakhm, hence the name given it. The founder of the dynasty was 'Amr, whose son Imru' al-Qais (not to be confused with the famous poet Imru' al-Qais who lived in the 6th century) converted to Christianity. Gradually the whole city converted to that faith. Imru' al-Qais dreamt of a unified and independent Arab kingdom and, following that dream, he seized many cities in Arabia. He formed a large army and developed the Kingdom as a naval power, which consisted of a fleet of ships operating along the Bahraini coast. In 325, the Persians began a campaign against the Arab kingdoms. They crushed the Lakhmid army and captured the city al-Hirah.