Mormon tells us that what was taught was “the records and prophecies.” These are certainly the records of the Nephite gospel, and probably the brass plates as well. Although the Nephite defectors among the Lamanites apparently had some kind of copy of the brass plates, since they held to the brass plate gospel without the continued revelation in the New World, the majority of the Lamaintes tdo not appear to have had the brass plate records. Of course, this makes sense since those records went with Nephi when the brother’s split into two groups.
Application: Having the door opened, the sons of Mosiah find success in their missionary endeavors. Even in places that seem unlikely, there are individuals waiting for the gospel. Among the Lamanites, many of whom may have had the same hatred for the Nephites as the king of the Lamanites demonstrated before Ammon (Alma 20:13), there were still many who were prepared for the message of the Lord. In modern days, we see the same thing with the opening of missionary efforts in countries formerly under communist rule. While the official ideology may have been unfavorable to the preaching of the gospel, it is among the people that success is found, and there have been those in such regimes who have been waiting for the word.