The Leningrad Codex is the oldest complete manuscript of the entire Hebrew Bible, written in Cairo and dated by its own colophon to 1008 or 1009 CE. It belongs to the Tiberian Masoretic tradition of Aaron ben Asher and was copied by a single scribe, Samuel ben Jacob, who wrote the consonantal text, added the vowel-points and cantillation, and supplied the marginal Masoretic notes, an unusual concentration of the whole task in one hand that gives the book a remarkable internal consistency.
Its name comes from St Petersburg, which was called Leningrad through the Soviet period; the manuscript has been held there, in what is now the National Library of Russia, since the 19th century. Although the Aleppo Codex is somewhat older, its loss of most of the Torah left the Leningrad Codex as the oldest complete Masoretic Bible in existence. For that reason it was adopted as the base text of the Biblia Hebraica editions, the standard scholarly printings of the Hebrew Bible, and so stands behind a great deal of modern biblical study and translation.