Mosiah1 finds the people of Zarahemla. The king of that land was named Zarahemla, and so was the city. The typical practice in the area was to name a city for the founder, as Alma explains about the city and land of Ammonihah in Alma 8:7. This would suggest that the city of Zarahemla had been founded within the current generation. It is possible that Zarahemla was named for a distant king, but Mesoamerican data suggest that there were a people who were of a different language and culture than those who would have been the Nephites and who had moved into that region during that approximate time range.
We will learn later that this people descended from Mulek, but we do not see the name Mulek in Amaleki’s account. The history is given, but not the name of the ancestor who left Jerusalem at a similar time to Lehi’s family. Just as the Nephite ancestor had come from Jerusalem, so did the people of Zarahemla. This provided one means of creating the merger among two otherwise different people.
Why would the people of Zarahemla not only accept the Nephites, but defer rulership to Mosiah1? Verse 14 tells us that the people of Mosiah arrived with the plates of brass. There were other sacred artifacts, but the presence of this particular artifact not only tied the Nephites to the Old World, but did so with a physical authority. Having those relics would have provided a superior claim to leadership. The plates of brass, along with the other artifacts, will be seen being passed through the line of the kings and the chief judges. They became the symbols of an authority that reached to the Old World.