The Torneo de las Naciones (Nations Tournament) is a friendly basketball tournament held in Spain co-organized by the basketball federations of Basque Country, Catalonia and Galicia. This three regional teams participate each year in a Final Four format with an invited national team.
The players who play the tournament are not called with the Spanish national team, and the invited teams usually don't participate with their best players.
References
Torneo de las Naciones Wikipedia(Text) CC BY-SA