Bible chronology deals with fixing the exact dates of the various events recorded. For the earliest parts of Old Testament history we rely entirely on the scripture itself; but the Hebrew Bible, the Septuagint or Greek translation, and the Samaritan Pentateuch do not agree together, so that many dates cannot be fixed with certainty. From the time of David onwards we get much assistance from secular history, such as inscriptions on monuments and other state records. Much work has still to be done in this direction. The dates found at the top of many printed English Bibles are due to Archbishop Ussher (1581–1656). Some of them have been shown to be incorrect.