By last week, most Christians in Mosul had already taken a fourth option—evacuation. Their departure marks the end of a continuous Christian tradition in Mosul. For thousands of years, Mosul has been a center for Christians, particularly for Assyrians, an ethnic group that predates the Arab conquest of Mesopotamia. Indeed, the ancient Assyrian capital of Nineveh, where the Prophet Jonah preached, lies across the Tigris River. Christianized in apostolic times, Assyrians have divided over the centuries into a number of communions that reflect the history of the religion: the Assyrian Church of the East, a small body, historically associated with Nestorianism, which once spread as far as China; the Syriac Orthodox Church, a member of the Oriental Orthodox family; and the Chaldean-rite Catholic Church, in communion with Rome. A small number of Assyrian Protestant churches exist as well, the legacy of nineteenth-century American missionaries.