Columbus main goal was spreading Christianity as well as finding a shorter path to the orient.
https://www.amazon.com/Columbus-Quest-Jerusalem-Religion-Voyages/dp/1439102376/ref=nodl_
Read this in college for a history class and wrote a paper on it.
Blame Religion and it’s cult like ideologies for why Columbus thought and acted the way he did
I just finished The Vikings by Niel Oliver and really enjoyed it. So much I didn't know about the Viking peoples as the extent of my knowledge about them was limited to the 20 min of talk that Leif Erikson gets in American high school history class, what I've read about the 9th and 10th century Danes in England and what I've seen in pop culture. It was really cool to learn about them trading with Arabs and Chinese and even playing a role in early Russian history.
I spent a few weeks in Cusco, Ollyantaytambo and Aguas Calientes, it was incredible. Prior to that I have studied the English explorer Percy Fawcett who spent a lot of time in S. America. In a book written by his son Brian Fawcett, who compiled all sorts of information and diary entries from his father. He has a couple anecdotes about a certain purple flower that had properties which allowed it to "melt" stone and iron. This is the book I am referring to, it's a very interesting read.