In the Brown case, the "separate but equal" principle was challenged.
Explanation:
Brown v. Board of Education (1954), a case filed by Oliver Brown after his daughter was not allowed to enter any white elementary school in Topeka and was forced to study in a less prepared school, became one of the most important cases in the American history because it challenged the "separate but equal" principle by demonstrating that the 14th amendment was violated under this clause because in reality schools were not equal denied African American children the opportunity to prepare themselves for a better future.
Segregation in public schools was then stated as unconstitutional because it didn't provide equal opportunities for children.
Jared Diamond put forth the idea that the Spanish were able to acquire steel swords because of their close proximity to the fertile crescent, who had invented the technology necessary to wield and mold steel. The Incans were a world away and so did not benefit from the technological advancement in regards to steel.
