I learned that friends, no matter how close you are with them, they will come and go.
The sentence is not listed, but the word impending means something that is about to occur (synonyms include upcoming, coming, near, to come, on the way etc.)
so the reason why an author would expand all that is because of history we had to know everything about the history of the Americas so we had the right religion we where before anything happens and we also had to know how they behaved to see how we had improved