Complex sentence: The Church of Mary in Ephesus may be one of the earliest Marian churches and is dated to the early 5th century, coinciding with the Council of Ephesus in 431.
Split into simpler sentences: The Church of Mary in Ephesus may be one of the earliest Marian churches. It is dated to the early 5th century, coinciding with the Council of Ephesus in 431.