And now the priests of king Noah, being ashamed to return to the city of Nephi, yea, and also fearing that the people would slay them, therefore they durst not return to their wives and their children.
And having tarried in the wilderness, and having discovered the daughters of the Lamanites, they laid and watched them;
And when there were but few of them gathered together to dance, they came forth out of their secret places and took them and carried them into the wilderness; yea, twenty and four of the daughters of the Lamanites they carried into the wilderness.
reads Mosiah 20:3-5. Why are the priests in the wilderness in the first place? Where do we first meet them?
And they were about to take the priests also and put them to death, and they fled before them.
In Mosiah 19:21, the priests didn’t want to be killed by the Lamanites, so that’s why they fled.