Bronze Age New World (was: what if)

There are numerous alternate history websites. I like Bronze Age New World, a collective friction project with an assumption a group of Caribbean Indians had developed Polynesian-type navigational skills, leading to faster technological advances and more intensive communications across the Americas (similar to what Greeks and Phoenicians did in the Mediterranean). They gradually sailed up and down from Delaware to Brazil, raiding, trading, and cross-fertilizing ideas, then eventually reached California via the Pacific Ocean. Europeans arrived on schedule. Comparing to our time line, they find the natives have advanced bronze-age technology, urbanized kingdoms, and American brewed diseases.