As the Crown of Castile was much more important, powerful and rich than the Crown of Aragon (Aragon, Valencia, Catalonia and the Balearic Isles), it became Spain's main language.
2. People born in the Spanish regions of Castile-La Mancha (Castilla-La Mancha), Madrid, Cantabria, La Rioja and the provinces of Castile and Leon (Castilla y León) which belonged to the Kingdom of Castile until Castile and Leon rejoined in 1230 (Burgos, Ávila, Segovia, Palencia, Soria and Valladolid)
2. I was born in Cuenca, so I am Castilian.
Paul: Hi, Zek, I'm pretty good, thanks!
Ezekiel: why are you so nervous?
Paul: I'm not nervous, I'm just in a hurry... I have to go to my Castilian Class... sorry but I have an exam tomorrow and I have my books of Castilian in my house!! Bye!