The role of Manama as a regional port city in the Persian Gulf made it a hub for migrant workers in search of a better living. As a result, Manama has often been described, both in the pre-oil and post-oil era, as a cosmopolitan city. In 1904, it was estimated that Manama's population numbered 25,000, out of which half were believed to have been foreigners from Basra, Najd, al-Hasa and Iran, as well as from India and Europe.