I wish we knew more about ancient America. It is troubling to see South American ruins without detailed history to go with them.
The decipherment of written Mayan has revolutionized the study of precolumbian central America, but precolumbian Andean writing doesn't appear to exist -- apart from quipu, which may have been a mnemonic system or even an accounting system, rather than a system of sort-of writing. Writing from precolumbian North American contexts is limited to short inscriptions left by ancient navigators from elsewhere. Even the purported Mayan colony in, hmm, Georgia I think, has no known inscriptions in it.