Arrano beltza

Today, it is mostly used by Basque nationalists as a symbol of sovereignty and independence.

The black eagle was originally the seal of King Sancho VII of Navarre but was later attributed to Sancho III of Navarre who, when incorporating Aragon and Castile, had under his crown all the territories of Basque culture and language, including those traditionally Castilian, since his kingdom reached from Galicia to Ribagorça.

From a Basque nationalist interpretation, the rule of Sancho III constitutes a historical precedent for the aspirations of the unification of the Basque-speaking territories under one independent State.

For this idea, they allege that Sancho III ruled most of Christian Spain, from León to Barcelona, and that he was cited as Rex Hispanorum Regum, that is, "King of the Kings of the Hispanians".

Arrano beltza is also a song by Basque songwriter Mikel Laboa (later covered by rock band Negu Gorriak), including the verses: It alludes to a legend about the origin of the coat of arms and flag of Navarre.