In a Mesoamerican context, Mormon would be pointing his literary finger at the city of Teotihuacan, which was nearing its peak of power during Mormon’s day. It was in Central Mexico, where there was a large lake and many rivers, although the lake is now drained and completely covered by Mexico City.
The lack of timber is also interesting in its connection with building with cement. Teotihuacan extensively uses real cement in its buildings, and the process of creating the cement required burning large amounts of wood. Thus, there was a direct correlation between the lack of timber and the building in cement, with the direction of causation the reverse of what Mormon implies. The building in cement likely caused the lack of trees rather than the lack of trees requiring the alternate building method. Nevertheless, a land with a lack of trees, as well as many bodies of water, was an accurate description of Teotihuacan in Mormon’s day.
The composition of the city of Teotihuacan shows that there were divisions in the city where there were areas inhabited by different peoples who were not native to Central Mexico. There were areas, for example, where the evidence is that there were Maya in residence. The Maya cultures would probably have been those influencing at least the Lamanites, which demonstrates that there was a northern flow of population from what we believe were Book of Mormon lands to that city. Thus, it was probably accurate that some of the people of Ammon also went north.
We will see that it is the Teotihuacan of Mormon’s day that interests him, and that he would know the city well. Since this is an inserted text, it would be based on his own understanding rather than anything he had seen in the large plates for Helaman’s time period.