When and why did Mosiah1 leave the land of Nephi? Using the reasoning established previously, we can say that if Amaleki was "born in the days of Mosiah" (Omni 1:24), then Mosiah1 might have departed the land of Nephi and established himself as king over all the people in Zarahemla sometime between the years 397 and 406 (since Lehi left Jerusalem). [See Appendix A].
The reason that Mosiah1 left the land of Nephi might have been over a royal dispute regarding inheritance or politics. Although we only have record that Mosiah1 reigned as king over the people in the land of Zarahemla (Omni 1:12,19), there might be more to the picture. There had to have been grave political ramifications surrounding Mosiah1's ultimate possession of the sacred items associated with Nephite kings (Mosiah 1:15-6, 2 Nephi 5:14, Jacob 1:10). Some scholars have assumed that Mosiah1 smuggled these items away from the king of Nephi at the time; however, one has to wonder if Zarahemla and the Mulekites would have graciously accepted an imposter to the throne, especially after Zeniff as a scout (Mosiah 9:15), Limhi and his people (Mosiah 22:11-14), and Alma1's group (Mosiah 24:24-25) had a chance to set the record straight upon their return to Zarahemla. If we ignore the idea of symbols of kingship as a reason for Mosiah1 being established as king in Zarahemla, we are left to ponder other reasons that seem to be negated by the scriptural account:
1. Righteousness--but the Mulekites denied the being of their creator (Omni 1:17).
2. Numerical superiority--but the Nephites weren't half as numerous as the people of Zarahemla (Mosiah 25:2).
3. Influence of ideas--but the Nephites could not understand the people of Zarahemla (Omni 1:17).
Whatever the case, whether Mosiah1 had already ascended to kingship in the land of Nephi or not, he was probably the rightful heir because it is unlikely that he would or could take the large plates (kept by the kings--Omni 1:11, Words of Mormon 1:10-11), the Liahona, the Brass Plates, and the Sword of Laban (see Mosiah 1:15-16) under any other circumstances. In addition, it is unlikely that Zeniff would be allowed to muster support to return to "the land of our father's inheritance" (Mosiah 9:1) unless it was clear that Mosiah1 had a solid claim to the throne (see Mosiah 9:3). [Alan C. Miner, Personal Notes]