Textual: As noted at the end of chapter 9, there is no chapter break here in the 1830 edition. Mormon’s editing kept this chapter with the previous one.
Historical: The aftermath of the successful driving of the Lamanites from the lands of Nephi and Shilom results in “establish[ing] the kingdom.” This phrase further emphasizes that the victory was territorial as much as it was a victory of manpower. Zeniff has firmly established his borders.
The second piece of information is that he begins to stockpile arms. Thus further emphasizes the relative lack of preparation noted in Mosiah 9:16 (remember the import of the word “invent” in that verse as the creation of arms rather than the invention of new armament). Zeniff rightly supposes that he might be the focus of further retaliatory attacks, and is preparing his people against that eventuality.