Since Darius I did not establish himself in Babylon until defeating the rebel Nebuchadnezzar III in December of 522 and shortly afterward capturing and killing him in Babylon, the year 522 B.C.E. may be viewed as the accession year of King Darius I. Since the regnal year of a Persian king began in the spring month of Nisan, the first regnal year of King Darius I would begin in the spring of 521 B.C.E., as presented in Babylonian Chronology 626 B.C.–A.D. 75 (page 28), by Parker and Dubberstein. In that case the sixth regnal year of King Darius I began April 11-12, 516 B.C.E., and continued to the end of the twelfth lunar month (Adar) of his sixth year, or to the end of March of 515 B.C.E. On this basis, the rebuilding of the temple was completed by Zerubbabel on March 5-6 of 515 B.C.E.