The Aleppo Codex was once the oldest complete copy of the Masoretic Text, but now is missing its Torah section. The codex was written in the 10th century (around A.D. 920 in Palestine) and is considered by some to be the most authoritative document in the masorah ("transmission"), a tradition by which the Hebrew Scriptures have been preserved from generation to generation.
The name of the scribe who wrote the text of the Aleppo Codex is Shlomo Ben Boya’a, and the well-known Masorete Aharon Ben Asher added the vowels, the cantillation marks, and the Masoretic commentary. This information emerges from the dedication of the Aleppo Codex, which was written at the end of the manuscript about a hundred years after its completion, when it was dedicated to the Karaite community of Jerusalem.
The exact date of the writing of the Aleppo Codex is unknown, because the manuscript does not contain a colophon (the scribe’s afterword, containing details about his identity and the time and place of the writing).
The dedicatory inscription, which was in the last part of the Aleppo Codex, shows that it was dedicated to the Karaite synagogue in Jerusalem. It states that Yisrael Ben Simha of Basra dedicated the Aleppo Codex to the Karaite community of Jerusalem and placed it under the guardianship of two Karaite leaders, Yoshiahu and Yehezqiyahu.