Name the monarchs who united Spain and made it a powerful nation?

Answer 1

Isabella of Castile-Leon and Ferdinand of Aragon defeated the last of the Moors, then evicted them and the Jews.

They DID NOT unite the three kingdoms. Isabella and her descendants remained the only monarchs of Castile-Leon and Ferdinand and his descendants were the only monarchs of Aragon.

Carlos I of Spain, their grandson, inherited all three kingdoms in 1516. Carlos I of Spain was also know as the Holy Roman Emperor Charles V. That was the genesis of modern Spain.

Answer 2

Ferdinand of Aragon and Isabella of Castile did not unify Spain. They ejected the Moors and the Jews. Each was the sole Monarch of their respective Kingdoms but they did NOT rule in the spouse's kingdom.

The three kingdoms of Castile, Leon, and Aragon were first ruled by one monarch when their grandson, who was both Carlos II of Spain and also Charles V Ho;y Roman Emperor, inherited all three in 1516. That was the beginning of what eventually became Spain.