Virtually all non-Muslims in Oman are foreign workers. Non-Muslim religious communities include various groups of Jains, Buddhists, Zoroastrians, Sikhs, Jews, Hindus and Christians. Christian communities are centred in the major urban areas of Muscat, Sohar and Salalah. These include Catholic, Eastern Orthodox and various Protestant congregations, organising along linguistic and ethnic lines. More than 50 different Christian groups, fellowships and assemblies are active in the Muscat metropolitan area, formed by migrant workers from Southeast Asia.