The galaxy's first professional Nuna-Ball League (NBL) was established by Lysko Buelia and a group of investors, during the years leading up to the Clone Wars.
Teams in the league were made up entirely of droids, with new models of droids being grouped into teams and pitted against each other in matches that mimicked the organic sport.
Droid manufacturers liked this format for many reasons, one of which was the minimal cost involved in fielding a team versus the monetary rewards of the sport's popularity.