Founded in 1975, it is the first professional basketball league in Asia and is the second oldest continuously professional basketball league existing in the world after the NBA, established before the “open era” of basketball in 1990 where FIBA allowed longstanding domestic leagues, which mostly had predated the PBA, to become professional.

The Philippine Basketball Association was founded when nine teams left the now-defunct Manila Industrial and Commercial Athletic Association (MICAA), which was tightly controlled by the Basketball Association of the Philippines (BAP), the FIBA-recognized national association at the time.

The PBA was formed when nine teams left the Manila Industrial and Commercial Athletes Association (MICA), an association closely controlled by the Basketball Association of the Philippines (BAP), the national association recognized by FIBA in at that moment. At that time, the basketball tournament in the Philippines was still considered an amateur tournament by law, and because of many dissatisfactions with MICAA, the 9 management companies of the 9 teams split up and established their own PBA.

The first game of the league was held at the Araneta Coliseum on April 9, 1975, featuring Mariwasa-Noritake and Concepcion Carrier. 

The rules of the PBA are a combination of the rules of the NBA and FIBA. The tournament is also limited to natural-born Filipino citizens born in the Philippines. There are player quotas for natural-born Filipinos born outside the Philippines, while naturalized Filipinos and foreigners can only play in certain conferences.

Since the teams do not represent geographical areas, the main league will rent out the competition venues. A majority of games are held in the Smart Araneta Coliseum in Quezon City and the SM Mall of Asia Arena in Pasay. When both arenas are unavailable, the alternate venues are the Ynares Center in Antipolo, Rizal, PhilSports Arena in Pasig, and the Filoil EcoOil Centre in San Juan.

According to Wikipedia.