What is the black legend?

A black legend is a historiographical phenomenon in which a sustained trend in historical writing of biased reporting and introduction of fabricated, exaggerated and/or decontextualized facts is directed against particular persons, nations or institutions with the intention of creating a distorted and uniquely inhuman image of them while hiding their positive contributions to history. 

The Black Legend (Spanish: La Leyenda Negra) is a style of historical writing or propaganda that demonizes the Spanish Empire, its people and its culture.