But in 2010, a report on NPR showed that Joseph Smith's account of Zelph is consistent with what was discovered just a few years ago in Indiana--a site not far from the route of Zion's Camp.
1. Artifacts from the Rocky Mountains found in Indiana.
2. Evidence of connections between ancient North America and Mesoamerica (the hinterlands).
3. Evidence of pre-Columbian smelting in North America.
The latest thinking among Mesoamerican proponents regarding Zelph is probably Mark Allen Wright's proposal that North America was the "hinterlands" of Book of Mormon geography. [Note: I actually like the "hinterlands" approach, but I think it's inverted; i.e., Mesoamerica is the hinterland.]
One of the best analyses of Zelph was published by Donald Q. Cannon, here. He cites the journal entries, such as this one by Wilford Woodruff:
"He was a warrior under the great prophet /Onandagus/ that was known from the hill Camorah /or east sea/ to the Rocky mountains."
Whether it was Zelph or Onandagus who was known across the continent is unclear, but Reuben McBride also mentioned the Rocky Mountains.
I haven't had time to determine whether, in 1834, it was common knowledge that the Hopewell people imported products from the Rocky Mountains, but it seems to be a newsworthy item today.
Here's an excerpt from the 2010 NPR report about the Mann site in Indiana.