The Samaritans, adherents of a heterodox sect of Judaism who have worshipped and brought sacrifices on Mount Gerizim in Samaria since at least the 1st century BCE, possess their own version of the Torah that differs at various points from the Masoretic text (the version used by all other branches of Judaism). Examining the evidence from ancient manuscripts of the Bible discovered in the 20th century, Terry Giles speculates on the genesis of the Samaritan Pentateuch:
[Ancient] manuscript evidence, some of it dating back to the 3rd through 1st centuries BCE, indicates that the Samaritan Pentateuch is an extension of an earlier text-type, currently labeled the pre-Samaritan text, found in the Judean desert along with manuscripts of a version that would later become the Masoretic text and manuscripts similar to the Septuagint [the ancient Greek translation of the Bible]. The Samaritan Pentateuch provides an important witness to the early textual history of the first part of the Hebrew Bible. It was considered authoritative by at least some of the New Testament writers, and it remains the sacred text of the Samaritan community. . . .
The pre-Samaritan texts from the Judean desert are characterized by many of the editorial features found in the Samaritan Pentateuch (including . . . emphasis on the role of Moses and similar grammatical forms and spelling), but without the veneer of sectarian features favoring the Samaritan religious sect. The cumulative evidence points to the conclusion that the Samaritan Pentateuch is the product of a sectarian editing of the pre-Samaritan text-type, probably produced in the 1st century BCE through the 1st century CE.
More about: History & Ideas, Masoretes, Samaria, Samaritans, Septuagint, Torah