The Nehemiah Memorial, chapters 1–7 and 11–13, may have circulated as an independent work before being combined with the Ezra material to form Ezra–Nehemiah.[7] Determining the composition of the Memorial depends on the dates of Nehemiah's mission: It is commonly accepted that "Artaxerxes" was Artaxerxes I (there were two later kings of the same name), and that Nehemiah's first period in Jerusalem was therefore 445–433 BC;[8] allowing for his return to Susa and second journey to Jerusalem, the end of the 5th century BC is therefore the earliest possible date for the Memorial.[9] The Nehemiah Memorial is interrupted by chapters 8–10, which concern Ezra.