We find the following at the beginning of the book of Fourth Nephi:
And it came to pass that the thirty and fourth year passed away, and also the thirty and fifth, and behold the disciples of Jesus had formed a church of Christ in all the lands round about. . . . And it came to pass in the thirty and sixth year, the people were all converted unto the Lord, upon all the face of the land, both Nephites and Lamanites . . . (4 Nephi 1:1-2)
Assuming that the land of Bountiful where Christ appeared at the temple (3 Nephi 11:1) was the centerplace of the Church, then the Church apparently spread to "all the lands round about" the land of Bountiful. If the gospel had been preached and the Church organized in every local land which the Nephites and Lamanites were known to inhabit at that time, one would have to wonder how, in the two years since Christ's visit (from the year 34 to 36--see 4 Ne 1:1-2), the disciples of Jesus could sufficiently cover the entire continents of North and South America, preaching, baptizing, and organizing churches in order for Mormon to say that "the people were all converted unto the Lord, upon all the face of the land, both Nephites and Lamanites" (4 Nephi 1:2). On the other hand, by assuming a Mesoamerican setting, the distance and logistic conditions of this missionary undertaking could have been met quite nicely. We would be dealing in hundreds of miles instead of thousands of miles. [Alan C. Miner, Personal Notes]
Geographical [Theory Map]: 4 Nephi 1:1-2 All Converted in All the Land (34 A.S.--36 A.S.)