Castilian (Civ3)/Civilopedia

Castile originated, as most medieval kingdoms did, from a series of individual districts and fiefdoms. In 970 C.E. Fernando Gonzalez effected this unification but did not crown himself king; instead he called his new domain the county of Castile, with himself as Count. Shortly after Gonzalez' death, the king of Navarre decided to make official the political reality of the preceding generation, and split off Castile as its own kingdom, distinct from Leon, with his son Ferdinand as monarch (but both Castile and Leon still owed fealty to the Navarro crown). It was at this time that the fighting spirit of Castile became apparent, as it took center stage in the Reconquista, the crusade to Christianize Spain and eject the Moors entirely.
A central figure during this time was Rodrigo Diaz. Diaz, a local landowner and soldier of Castile, accompanied Ferdinand's son Sancho -- a friend since childhood -- on several campaigns against the Moors, distinguishing himself as a warrior, tactician, and leader of men. Unfortunately, Sancho was killed in one of those campaigns, and Diaz returned to court. Sancho's death reunited the thrones of Castile and Leon (under his brother Alfonso VI), which had been separate entities since old Ferdinand's death. The Castilian nobility was not pleased at the prospect of returning to what they perceived as outside rule. Diaz hated court intrigue, and when the opportunity came to go on campaign again, he seized it. After a successful campaign, in which he further distinguished himself and raised his reputation in the eyes of both his enemies and friends, the increasingly rash Diaz led a raid into the kingdom of Toledo, which Alfonse VI had promised not to attack. For this, Diaz was exiled. However, his reputation was so high among the Muslims -- they referred to him as "al-sayid", meaning "lord". This nickname caught on, and his countrymen pronounced the sobriquet as "El Cid".
El Cid decided to offer his loyalty to the Muslims he had fought against for so long. A condition of his exile was that he could not lead troops in battle against Leon or Castile, but that did not stop him from leading the Muslim armies of Saragossa against other Muslim states. Eventually he was (grudgingly) recalled by Alfonso, and served his rightful lord once again, but his goals lay elsewhere. At the end of his life, he ruled Valencia, a wealthy and powerful city-state in southeastern Spain.
The campaigns of El Cid hastened the end of Muslim power in Spain, which finally came about (except for a tiny foothold in Granada) towards the end of the 12th century C.E. Castile continued to prosper, and in 1479 the Princess Isabella confounded a plot against her family by secretly arranging her own marriage to Ferdinand of Aragon. The resulting dynastic union created a great power, which quickly annexed old Navarre and proceeded to dominate world affairs for over a century.