Not much in this section will be different from OTL.
Columbus Turns to the Spanish Court
In our history, Columbus first goes to Portugal to seek funding for his voyage to find an easier route to Asia. When turned down, Columbus goes to Spain, where he gets money to sail west to the New World, where land is claimed for Spain. In this timeline, Alfonso will question if Columbus is worthwhile, but is persuaded by Queen Isabella, who wants riches, to fund the expedition. Columbus lands in the Caribbean like in OTL, seizes land from the Natives and sets up the first Spanish Colonies. The Gateway to Spanish Domination lies open.