I wish I could find my copy of Clendinnen's Aztecs, but, considering how trade was completely necessary for the survival of the Aztecs (not so much trade as in mutual exchange, but more tribute from conquered peoples), but they at least had contact with people in the former Mayan territories, as well as peoples as far south as Panama.

However, if we look at Central America, the Darién Gap, in modern-day Panama/Colombia, is very inhospitable swamps, so crossing there would be ineffective and dangerous.

Neither the Incans nor the Aztecs were known for sea-travel, most objects that came from the sea came to both empires from other groups through tribute.

Again, wish I could find my Clendinnen book for sources, but it seems I've misplaced it.

I remember this question was asked a few weeks ago and the answer was that the Incas and Aztecs kept to their respective areas in South/Central America and didn't have much reason to venture outside their empires so they didn't contact each other

Mods, feel free to delete this if it's not accurate enough

Or the Hopewell civilization?