Haha, yeah, the idea was the first book covered the Americas and it's native people before Columbus (and white folks in general) arrived, so 1491. He admits early on that folks had arrived before 1492, but decided it was a more recognizable year.

And then the second book covered how global trade and traffic started changing the world after the arrival of other folks in the Americas, but it wasn't about the arrival itself, so 1493.