1. POLITICAL CHANGE IN THE 13 TH AND 14 TH CENTURIES -
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THE CROWN OF CASTILLA Castilla and Leรณn had been closely connected in the 11 th and 12 th centuries when they were often ruled by the same monarch. In the 13 th century the two kingdoms were definitively united by Fernando III of Castilla in 1230. Under Alfonso X El Sabio, Castilla reached important cultural achievements. Alfonso X was a great patron of the arts and promoted learning based on classical, Arabic and Hebrew sources. The powerful Castilian aristocracy received huge areas of conquered Muslim land during the Reconquest. By the 14 th century, the great nobles rivalled the king in power and influence. This caused tensions and a civil war between Pedro I and his half-brother Enrique de Trastรกmara. Enrique was suported by the leading nobles, and the war ended with the creation of a new Trastรกmara dynasty.