The Ontario Hockey Association Tier II Junior "A" League was born out of the creation of the Ontario Hockey League. There have always been multiple tiers of junior hockey, but the top tier, then known as Ontario Hockey Association Junior "A", elected to split from the OHA and create its own level of hockey. The early 1970s sparked a vast reorganization of Canadian hockey right across the country. The OHL was born out of this, as well was the Western Hockey League and the Quebec Major Junior Hockey League in other parts of Canada. The new tier was known as Major Junior "A" hockey. The first Ontario Tier II League came in 1968 with creation of the renegade Western Ontario Junior A Hockey League, which became the Southern Ontario Junior A Hockey League in 1970.
The aftermath of the annexation of the top tier left a vacuum for a new top tier of OHA hockey. What filled the gap in 1972 was the 12-team Ontario Hockey Association Jr. "A" Hockey League, comprised of 5 teams leaving the Metro Junior "B" (the Richmond Hill Rams, North York Rangers, Downsview Beavers, Aurora Tigers and the Dixie Beehives), 6 expansion teams (Seneca Flyers, Ajax Steelers, Wexford Warriors, Vaughan Nationals, Weston Dodgers, Kingston Frontenac's) and the North Bay Trappers of the recently folded Northern Ontario Junior Hockey League.