There are some questions that need to be answered regarding Nephi's account of his father Lehi's prophecies. Nephi asserts that, "six hundred years from the time that my father left Jerusalem, a prophet would the Lord God raise up among the Jews--even a Messiah" (1 Nephi 10:4). Joseph Allen introduces the dilemma:
The traditional Book of Mormon dating for Lehi's departure from Jerusalem is 600 B.C., the first year of the reign of King Zedekiah/Mattaniah. Modern Biblical scholarship, as outlined above, places the first year of the reign of King Zedekiah/Mattaniah at 597 or 598 B.C. The question is, did Lehi leave Jerusalem around 600 B.C., or 597 B.C., three years later?
The issue is further complicated because Biblical scholarship places the birth of Christ at 4 B.C. If we use the 600 B.C. Lehi departure date, the birth of Christ would need to be at 1B.C./A.D.1
If the first year of the reign of Zedekiah/Mattaniah was 597 B.C. and if Christ was born at 4 B.C., why does the Book of Mormon say that in 600 years the Savior would be born? If we subtract 4 B.C. from 597 B.C., we come up with 593 years instead of 600 years. [See Appendix A]
Option #1:
The years from 597 B.C. (the first year of the reign of Zedekiah/Mattaniah and the departure of Lehi out of Jerusalem) to 4 B.C. (the death of Herod and the birth of Christ) are 593 years (365.24 days to the year). But 597 B.C. to 4 B.C. is 600 Maya years (tun, or 360 days).
Therefore, Lehi left Jerusalem at 597 B.C., in the first year of the reign of Zedekiah/Mattaniah. Six hundred Maya years later, Christ was born, which is the year 4 B.C.
Nephi was writing his record in Mesoamerica. The Book of Mormon record keepers [might have] adopted the tun year.
The Mesoamericans adjusted their calendar in A.D. 6 when a mass planetary conjunction occurred. This adjustment is consistent with the Book of Mormon wherein it states that nine years after the birth of Christ (4 B.C.), the people adjusted their calendar system in the beginning of A.D. 6 or at the end of A.D. 5 (3 Nephi 2:7-8) . . . (thus) all is well. Or is it? [Joseph Allen, Exploring the Lands of the Book of Mormon, p. 22] [See Appendix A]
Option #2:
According to a F.A.R.M.S. article by Jay Huber, even before the days of Lehi, a 360-day year had historical precedence. Many of the ancient calendars had a 360-day core. The Egyptian standard civil calendar, dating from the early third millennium B.C. consisted of a core of 12 months of 30 days each, with five extra days tagged onto the end of the year. In Mesopotamia a similar schematic calendar was used, although it never became dominant as it did in Egypt, being overshadowed by the lunar calendar. It is even speculated that the pre-exilic Israelite calendar used a 360-day base. [Jay Huber, "Lehi's 600-Year Prophecy and the Birth of Christ," F.A.R.M.S., p. 12]
The notion of a 360-day year has a number of interesting scriptural echoes. The apostle John, in the Book of Revelation, seems to equate 42 months with 3.5 "times" (or "years"; compare Rev. 12:14 with 12:6), as well as 42 months with 1260 days (Rev 11:2 and 3). Both usages seem to imply a 12 month "year" with 30 days per "month." Similarly the Genesis account of the flood implies the use of a thirty-day month in its equating the five "months" of the flood to 150 days (see Genesis 7:11-12, 24; 8:2-4) (p. 14).
In conclusion, only the 360-day year allows Lehi's 600-year prophecy to be fitted between Herod's death and Zedekiah's accession. Whether such a year length was fixed by revelation, by Old World tradition, or by personal preference is uncertain (p. 34). [See Appendix A]
Option #3:
Joseph Allen suggests that before we get too excited about a 597 B.C. departure date for Lehi, let us take a look at what was going on in Jerusalem at 597 B.C., which suggests that Lehi and his family had been long gone from their homeland.
1. Jehoiakim, who had been the king of Judah for 11 years, was thrown against the wall by the Babylonians and denied a burial in 598/597 B.C. The reason the Babylonians took such drastic action is that Jehoiakim did not send the last month's rent as had been agreed in a treaty three years previously. The Babylonians simply foreclosed on Jehoiakim. They took 3,000 of the principal leaders of Judah captive into Babylon (Josephus 217).
With this type of turmoil going on at 597 B.C. in Jerusalem we would expect Nephi to mention it in his account as opposed to just prophesying about it (1 Nephi 2:11).
In addition, if what we read above happened in 597 B.C., the gold and silver and land would already have been confiscated by Nebuchadnezzar. Laman and Lemuel would probably be grumbling in Babylon.
2. In the same year, 597 B.C., Nebuchadnezzar, the king of the Babylonians, placed the son of Jehoiakim, whose name was Jehoiachin, on the throne. However, fearful that the son might retaliate for his father's death, the Babylonians took Jehoiachin into captivity to Babylon after Jehoiachin had reigned for only three months and ten days.
The Babylonians carried away the king's mother, the king's wives, his officers, and mighty men of the land. The Babylonians also took captive into Babylon all the craftsmen and smiths and the mighty men of valor, consisting of 10,000 captives. Only the poorest part of the people were left at Jerusalem. (2 Kings 24:14-18). In this way, Nebuchadnezzar was assured of getting his tribute and of keeping Jerusalem under control.
Had Lehi and his family still been around in 598/97 B.C. when the above activity was taking place in Jerusalem, he and his sons, as well as Laban who had the brass plates, would have been deported into Babylon. They would certainly qualify as "men of valor" and would not be considered "the poorest sort of the people" (2 Kings 24:14).
Nebuchadnezzar had been the king of the Babylonians for four years. During those four years, he had carried on a Napoleon-type program wherein he gained control over Egypt, Syria, and a good share of the Mid-Eastern world. In the year 601 B.C., he marched with a mighty army to Jerusalem. In no uncertain terms, he informed Jehoiakim, who had been the king for eight years, that Jehoiakim needed to sign a treaty and to pay a heavy tribute to Babylon or Jerusalem would be destroyed on the spot. Jehoiakim complied with the request and paid tribute for three years, or until about 598/97 B.C. During the three years, the calm before the storm occurred. To the vain people, like Laman and Lemuel, peace was apparently guaranteed.
3. To extract 600 years [from a 601 B.C. departure date], we must place the birth of Christ at 1 B.C./A.D.1 [This] is not difficult to solve, as many scholars feel comfortable with a 1 B.C. birth date for Christ. (See the book April Sixth, by John Lefgren. See also the articles by John P. Pratt in The Ensign, 1985:59-68) [Joseph Allen, Exploring the Lands of the Book of Mormon, pp. 22-23] [See also John P. Pratt, "Lehi's 600-year Prophecy of the Birth of Christ, Http://[www.meridianmagazine.com/articles/000331sixhundred.html]] [See the commentary on 1 Nephi 1:13; 10:4] [See Appendix A]
Option #4:
According to Randall Spackman, if we follow the latest scholarly research, the first year of the reign of Zedekiah (and therefore the earliest time at which Lehi could have departed Jerusalem) was 597 B.C.E. This creates a problem: 600 years from 597 B.C.E. does not correlate with the time of the birth of Christ. The principal timekeeping system throughout the Middle East in the sixth century B.C.E. was a 12-moon calendar (which averages 354.36705 days per year). The priests also recognized that the solar year (365.2422 days) was about 11 days longer than the 12-moon calendar. In Lehi's days, a thirteenth moon was added (or "intercalated") to a year when it became clear that the religious festivals were starting to occur too early in the agricultural or seasonal cycle. However, it is unlikely that Lehi would have attempted to intercalate his calendar even for a short period of time because the methods used were secret and closely guarded by the priests of the temple. In the same way, the traditional calendar of the Arabian desert was a nonintercalated 12-moon calendar. In addition, with Lehi traveling through different climate zones, there would have been no constant seasonal frame of reference. Moreover, Lehi's descendants would have been in conformity with Mesoamerican astronomical and calendrical practice if they simply continued to count a 12-moon year. Thus, the 600 years of Lehi's prophecy appear to have been counted as 600 x 12, or 7,200 moons, a period of about 212,620.2 days or 582.13 of our solar years. As we shall find in future commentary, scholarly calculations place the birth of Christ around 5 B.C.E. If that is the case, then Lehi might have left Jerusalem almost right as the siege was lifted in January 587 B.C.E. [Randall Spackman, "Introduction to Book of Mormon Chronology," F.A.R.M.S., pp. 15-17]
Option #5
According to John Tvedtnes, it is very doubtful that we can take the "600 years" of Nephi's prophecy as literal, since Lehi left Jerusalem no earlier than the first year of Zedekiah (1 Nephi 1:4), which would have been 598 B.C.--already too late for the prophecy to have been fulfilled precisely 600 years later. Thus, Alma (see Alma 3:14-17) could have been aware of Nephi's statement and taken it as an approximation only, rather than as a precise date. It is Mormon's rewriting of the history which has the birth of Christ occurring in the six hundredth year (3 Nephi 1:1). And it was this same Mormon who acknowledged that there could have been errors in the chronology (3 Nephi 8:1-2). [John A. Tvedtnes, "Book Review of Jerald and Sandra Tanner, Covering Up the Black Hole in the Book of Mormon," in Review of Books on the Book of Mormon, FARMS, Vol. 3, 1991, p. 199]