The Apostolic Churches of the East is currently the only complete history in English of the Syriac Church of the East. It covers the periods of the Sassanians, Arabs, Mongols, Ottomans, and the twentieth century. While the Arabs conquered the Middle East in the seventh century, the East Syriac missionaries had already reached the court of the Emperor of China, and in the European Middle Ages, the Church of the East was geographically far larger than the Roman Catholic Church, with congregations in Central Asia and India. The Church of the East is now scattered all over the world, with faithful in the Middle East, Europe, the USA, India and Australia.