When was the first Spanish Grammar Book published?

In 1492, Antonio de Nebrija published Gramática de la lengua castellana, the first grammar book of the Spanish language. Works had previously been published on Latin usage, such as Lorenzo Valla’s De Elegantiis Latinae Linguae (1471), but Gramática was the first book to focus on the study of the rules of a Western European language besides Latin.

Digital version of Gramática de la lengua castellana.