Mosiah 25:1 - 25:5

Mosiah 25:1 And now king Mosiah caused that all the people should be gathered together.

King Mosiah gathers together all the people to announce the arrival of Alma.

Mosiah 25:2 Now there were not so many of the children of Nephi, or so many of those who were descendants of Nephi, as there were of the people of Zarahemla, who was a descendant of Mulek, and those who came with him into the wilderness.

Mormon makes note that there are far more descendants of the Mulekites in the gathering than there are Nephites.

Mosiah 25:3 And there were not so many of the people of Nephi and of the people of Zarahemla as there were of the Lamanites; yea, they were not half so numerous.

And when comparing numbers of the Nephite and Mulekites to Lamanites, they are only half their number.

Mosiah 25:4 And now all the people of Nephi were assembled together, and also all the people of Zarahemla, and they were gathered together in two bodies.

As the people of Mosiah gathered together, they divided themselves into two groups.
[I assume that they divided themselves into those who were Nephites and those who were Mulekites. Don’t know why, I guess we will always gravitate towards family and friends as we do nowadays when ever we have Stake get togethers. We seem to find our ward members and hang out with them even thought it is a Stake assembly.]

Mosiah 25:5 And it came to pass that Mosiah did read, and caused to be read, the records of Zeniff to his people; yea, he read the records of the people of Zeniff, from the time they left the land of Zarahemla until they returned again.

Mosiah had to records of Zeniff read to the crowd which covered the time Zeniff left Zarahemla until Limhi and his people arrived.
Alma may have not known of Limhi's escape so it would have been a reunion for the two groups. One can only imagine the stories exchanged by the members of these groups.}