There is no record of the exact number of visits from Moroni, but 22 have been documented (see H. Donl Peterson, "Moroni—Joseph Smith's Tutor," Ensign, Jan. 1992, 22–29).
Moroni taught Joseph Smith from scripture, quoting Malachi, Isaiah, Joel, and Acts. John Taylor explained: "Joseph Smith in the first place was set apart by the Almighty according to the [councils] of the Gods in the eternal worlds, to introduce the principles of life among the people. . . . The principles which he had, placed him in communication with . . . Abraham, Isaac, Jacob, Noah, Adam, Seth, Enoch, and Jesus and the Father and the apostles that lived on this continent as well as those who lived on the Asiatic continent. . . . Why? Because he had to introduce a dispensation which was called the dispensation of the fulness of times, and it was known as such by the ancient servants of God" (Deseret News Weekly, June 9, 1880, 280).
Joseph also learned about the ancient inhabitants of the Americas, "who they were, and from whence they came; a brief sketch of their origin, progress, civilization, laws, governments, of their righteousness and iniquity, and the blessings of God being finally withdrawn from them as a people" (History of the Church, 4:537).