It's funny that the Pac-12 claims to be the country's second-oldest major conference. The schools that made up the original Pacific Coast Conference - which included 8 of the league's current 12 members - disbanded in June 0f 1959. Four of those schools (California, USC, UCLA & Washington) formed a NEW CONFERENCE in July of that year, with Stanford coming aboard a month later. The new league was dubbed the Athletic Association of Western Universities. Washington St. came aboard in 1962, with Oregon & Oregon St. joining what would eventually be called the Pac-8 in 1964. Even though the new league would be comprised of essentially the same schools as the old one, it was still a new conference since the old one - which dated back to 1912 - had been disbanded.
Current major conferences that pre-date the erstwhile Pac-12 include the Big 10 (founded in 1895), the SEC (1933), and the ACC (1953). Another FBS league (but not a Power-5 league) that pre-dates the Pac-12 is the MAC, which was founded in 1947 as a small-college conference. Additionally, the MVC (which no longer sponsors football) dates back to 1907; and the Ivy League - which traces its lineage to 1901 - and the Southern Conference (1921) were considered Major College until they moved to the FCS (1-AA) level in 1982).
Glad you got that off your chest. Clearly been bothering you for quite some time.