“Thus Commenced the Reign of the Judges”

After Lehi left Jerusalem, time was reckoned according to the date of his departure-e.g., “fifty years after Lehi left Jerusalem,” or “four hundred years had passed away from the time that Lehi left Jerusalem,” and so forth. With the establishment of the system of the judges we encounter a new reckoning of time among the Nephites-the “first year of the reign of the judges,” the “fifteenth year of the reign of the judges,” and so on. This system would be in effect until the sign of the birth of Christ would be given, when they would begin reckoning their time from that point (see 3 Nephi 2:8).
Joseph F. McConkie, Robert L. Millet -

Joseph F. McConkie, Robert L. Millet

Doctrinal Commentary on the Book of Mormon, Vol. 2

References