WWF was built on all the regional circuits across the country. The article does have an error, it says Volkoff teamed with The Sheik. I remember the Sheik coming through Indy once in a while in the 70s, he was mostly a midwest guy who started in the 40s. Volkoff actually teamed with The Iron Sheik, who played an Iranian bad guy. I don’t remember Volkoff being in the midwest.
It actually started with Georgia Championship Wrestling in the 50 and 60s. Ted Turner bought the rights and made it national, with Rowdy Roddy Piper and the Vince McMahon bought it up and made the WWF.
Here is more:
https://en.wikipedia.org/wiki/Georgia_Championship_Wrestling