The discovery of the ancient Codices Vaticanus and Sinaiticus in the 19th century revealed that the New Testament circulated in three different textual traditions: the Byzantine, the Alexandrian, and the Western. It became clear that the Textus Receptus was based entirely on Byzantine manuscripts, all written in the high Middle Ages. Modern Protestant and Catholic bibles rely on the much older Alexandrian manuscripts, represented by Vaticanus and Sinaiticus, and on modern papyrus discoveries.