First Esdras contains the whole of Ezra with the addition of one section; its verses are numbered differently. Just as Ezra begins with the last two verses of 2 Chronicles, 1 Esdras begins with the last two chapters; this suggests that Chronicles and Esdras may have been read as one book at sometime in the past.
Ezra 4:6 includes a reference to a King Ahasuerus. Etymologicaly, Ahasuerus is the same as Xerxes, who reigned between Darius and Artaxerxes. Because this is anachronistic, some scholars identify it with another king. In 1 Esdras, this reference is replaced with the additional section. Thus, in 1 Esdras, Cyrus the Great, Darius the Great, and Artaxerxes I appear in their historical order.
The additional section forms the core of 1 Esdras with Ezra 5, which together are arranged in a literary chiasm around the celebration in Jerusalem at the exiles' return. This chiastic core forms 1 Esdras into a complete literary unit, allowing it to stand independently from the book of Nehemiah. Indeed some scholars, such as W. F. Albright and Edwin M. Yamauchi, believe that Nehemiah came back to Jerusalem before Ezra.
The book was widely quoted by early Christian authors and it found a place in Origen's Hexapla. It was not included in early canons of the Western Church, and Clement VIII relegated it to an appendix following the New Testament in the Vulgate "lest [it] perish entirely".[6] However, the use of the book continued in the Eastern Church, and it remains a part of the Eastern Orthodox canon.