I'm curious to what degree pre-Columbian civilizations aren't well understood due to the lack of evidence beyond our control, versus the lack of study/attention to the region. I imagine the dense and difficult terrain doesn't help either.

A huge part of the problem is the whole "burning every Maya book" thing that some spanish dudes decided to embark on. Various ethnic cleansing campaigns over the last two centuries or so, not to mention the impact of disease.

Its a real tragedy the colonizers didn't think to preserve the world they were conquering.