Joseph calls the Book of Mormon a record of "our western Tribes of Indians."
Joseph Smith, Letter to Noah C. Saxton, January 4, 1833, Joseph Smith Papers
The Book of Mormon is a reccord of the forefathers of our western Tribes of Indians, having been found through the ministration of an holy Angel translated into our own Language by the gift and power of God, after having been hid up in the earth for the last fourteen hundred years containing the word of God, which was delivered unto them, By it we learn that our western tribes of Indians are desendants from that Joseph that was sold into Egypt, and that the Land of America is a promised land unto them, and unto it all the tribes of Israel will come.