These verses report a large-scale migration out of the land of Zarahemla toward the north. Most leave on foot, but a smaller number embark with Hagoth.
From this point on, there is a general trend toward a northward Nephite migration, away from the bellicose and more numerous Lamanites who so recently had attempted to expand into Nephite territory. The pressure from the south is just beginning, and the exodus to the north does not seem coincidental.
Literature: It is also possible that Mormon emphasizes this northern movement for a literary purpose. I argue that Mormon sees a connection between people in the north and the development of the Gadianton bands who hasten the Nephite destruction during Mormon’s time. To make that connection, Mormon emphasizes the movement of Nephites, presumably with Gadiantons among them, northward. (See Helaman, Part 1: Context, Chapter 3: “The Gadianton Robbers in Mormon’s Theological History: Their Structural Role and Plausible Identification.”) It is certain that not all who go north represent the anti-Nephite religious and political philosophies, but Mormon will find it convenient to create that caricature.