1516 is an important date in the history of the Spains, as it is the year of the accession of Charles V. The Spains were not one country in this time; they were composed of: Each had its own laws and traditions and was not keen to change them. Castile and Aragon were merged in 1461 when King Ferdinand married Queen Isabella, becoming known as the "Catholic Kings". The Basque country was a small country on the border with France. Granada was an "emirate of Granada" in the south of Spain run by the Moors (Arabs). Sardinia, Sicily and Naples were all controlled by Aragon following King Ferdinand's wars. Although Castile was the biggest of the Spains, much of its territory was composed of mountains and therefore not that useful for farming or living on.

All the countries were geographically united. Attempts had been made to centralise the bureaucracy of the government, and Ferdinand and Isabella had restored order after a period of chaos. The Inquisition was an influence throughout all the countries, but was generally despised and more bothered about religious conformity than politics.

Ferdinand and Isabella had tried hard to present the image of unity, but in reality this was idealistic. The reality was that the Cortes (Spanish "parliaments") were different in each Kingdom, and each Kingdom cherished its identity and constitution. Although Castile was the dominant language, the other Kingdoms resisted it because they feared their identity would be swamped.

Economic barriers also existed between the Kingdoms: each had its own currency. New land and trade went to seperate Kingdoms rather than the Spains as a whole: trade from the New World went to Castile, for instance.

Many historians argue that the true unity of Spain came out during Charles V's reign, because:

  • One King ruled all the Kingdoms.
  • Troops fought abroad from all Kingdoms.
  • The Kingdoms finally had a common unit of currency: the gold ducat.
  • Royal administration was made up of councils based in Castile.