The Aleppo Codex (the Keter ("Crown") Aram Tzova) is the oldest complete manuscript Hebrew Bible, though scrolls of individual books of the Tanakh are much older (see Dead Sea scrolls). Thus the Aleppo Codex is the most authoritative source document, both for the biblical text and for its vocalization and cantillation, and for mesorah ("transmission"), the tradition by which the Hebrew Scriptures have been preserved from generation to generation. See also Masoretic Text.
The consonants in the Codex were copied by the scribe Shlomo Ben Buya'a in Palestine in the 10th century. The text was then verified, vocalized, and provided with the Masorah by Aaron ben Asher, the last and most prominent member of the Ben-Asher dynasty of grammarians from Tiberias, which shaped the most accurate version of the Masorah and the Bible. The Leningrad Codex, the other oldest complete Hebrew Bible, has been claimed as a product of the Ben-Asher scriptorium. However, its own colophon says only that it was copied from manuscripts written by ben Asher; there is no evidence that ben Asher ever saw it.
The Codex was the manuscript used by the rabbi and scholar Maimonides (1135-1204), when he set down the exact rules for writing scrolls of the Torah, Hilkhot Sefer Torah ("the Laws of the Torah Scroll") in his Mishneh Torah. This halakhic ruling gave the Aleppo Codex the seal of supreme textual authority. "The codex which we used in these works is the codex known in Egypt, which includes 24 books, which was in Jerusalem," he wrote.
The Codex has had an eventful history. In the mid 11th century, about a century after it was written, the text was delivered to the Karaite community of Jerusalem, apparently after having been purchased from the heirs of Aharon ben Asher. Not long after (either in 1079 by the Seljuks or in 1099 by the Crusaders) it was looted from Jerusalem and eventually wound up in the Rabbanite synagogue in Cairo, where it was consulted by Maimonides. Maimonides' descendants brought it to Aleppo, Syria, at the end of the 14th century. The Aleppo community guarded it zealously for some six hundred years. Indeed, it proved almost impossible for outsiders to examine it. Paul Kahle tried and failed to obtain a photographic copy in the 1920s. Almost the only person allowed to compare it with a standard printed Hebrew Bible and note the differences was Umberto Cassuto. This secrecy made it impossible to confirm the authenticity of the Codex.
During the riots against Jews and Jewish property in Aleppo in December 1947, the community's ancient synagogue was burned and the Codex was damaged, so that no more than 295 of the original 487 leaves survived. In particular, only the last few pages of the Torah are extant.
The missing leaves are a subject of fierce controversy. The Jews of Aleppo claim that they were burned. But scholarly analysis has shown no evidence of fire having reached the codex itself. Scholars instead accuse members of the Jewish community of having torn off the missing leaves and keeping them privately hidden. One "missing" leaf has turned up and been brought to Jerusalem since the anti-Jewish riots in 1947.
In January 1958 the Aleppo Codex was brought to Jerusalem, where it remains in the Shrine of the Book at the Israel Museum. This finally gave scholars the chance to examine it and consider the claims that it is indeed the manuscript referred to by Maimonides. The work of Moshe Goshen-Gottstein on the few surviving pages of the Torah seems to have confirmed these claims beyond reasonable doubt. The Aleppo Codex is the source for several modern editions of the Hebrew Bible, including "The Jerusalem Crown" (printed in Jerusalem in 2000, with a newly-designed typeface based on the calligraphy of the Codex and based on its page-layout).