The Masoretic text was completed in the 10th or 11th century AD. It is universally recognized as the authoritative and official version of the Tanakh and is used for the translation for the Old Testament in many Protestant Bibles.
Masoretes labored to ensure that the Hebrew Tanakh was transmitted purely and maintained such status over the years. The Dead Sea Scrolls encountered in 1947 contained a full manuscript of the book of Isaiah. When the 1100 year older Isaiah scroll was compared to the newer Masoretic text, substantial agreement was still clear. This was incredible historical evidence that the Masoretes practiced sound textual transmission producing little discrepancy.