I'm aware that in 1469 Spain was unified under the marriage of Isabella and Ferdinand. But it was still seen as separate kingdoms of Castile and Aragon. What I would like to know is when did they began referring to the kingdom as Spain? Had the region always been called that and so they adopted it? And was there a document or decree that named it so? I'm looking for the origins of the country's naming.
Thanks in advance.
It is said in the case of Spain that the identity of "Hispania" was forged abroad. But the roots were in the rule of Isabella and Ferdinand. As they came out victors in the War of Castilian Succession, they forced a settlement on Portugal that Portugal could no longer claim to be inheritor of the Hispania identity of old.
As far back as 1500, cries of "Santiago, España!" were used by Spanish soldiers in the tercios in Italy to signify their place of origin on the peninsula. But the identity was not uniquely based on ethnicity nor place of origin, as Italian soldiers in Spanish employ used the battle-cry "Santiago, Spagna!" as they fought in Rhineland! But it was clear to what they paid tribute to, and the use of the term stuck.
The use of "Spanish" as a shorthand was forged by the explorers, adventurers, and soldiers abroad. Conquistadors started to identify themselves as "Spanish" in contrast to the natives.
So in the case of Spain, its national identity was formed as a shorthand on one hand, and more importantly as a response to "other"-ness as they ventured outside of the peninsula and outside the continent.
-- M. J. Rodriguez-Salgado, Christians, Civilised and Spanish: Multiple Identities in Sixteenth-Century Spain, Trans. Royal Historical Soc., Vol. 8 (1998), pp. 233-251.