1. The original name of Spain's official language. Castilian was originally spoken in the County of Castile (Condado de Castilla)and, when Castile got independent from León, this language was spread as Castile conquered most of the Iberian Peninsula, the Canary Islands and part of America.
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)
1. Castilian was formed in the County of Castile.
2. I was born in Cuenca, so I am Castilian.