The Trastámara house won a namesake "succession" war in this state, which has merged several times with León.
One monarch from this state ordered the creation of a namesake set of astronomical tables that were used across Europe for centuries. One family that ruled this state originated from the illegitimate children of Eleanor of Guzmán, whose son was victorious at the Battle of Pontiel. A monarch from this state created a seven-part vernacular legal code and was succeeded by Sancho IV. With the help of John of Gaunt and Edward the Black Prince, a leader of this state nicknamed "the Cruel" defeated his half-brother at the Battle of Nájera. Members of this state revolted against Charles V in the Revolt of the Comuneros. The Trastámara house won a namesake "succession" war in this state, which has merged several times with León. For 10 points, name this Spanish region that was united by the marriage of its Queen Isabella to Ferdinand of Aragon.
One monarch from this state ordered the creation of a namesake set of astronomical tables that were used across Europe for centuries.
Kingdom of Castile