Which two breeds made the pitbull breed?

the first Colbys dogs were bred in England in 1886 but The pit bull's ancestry can be traced back to roughly the 12th century, when European hunters cross-bred the molossus, an early mastiff, with the Bellenbeiser, or bull-biter--which became known as the bulldog--was used to attack dangerous game animals. With their powerful jaws, bulldogs could penetrate a tough hide, slash muscle, crush bone, and grip like a vise. While other dogs could track wild boar and bear, only the bulldog had the mettle to clamp its jaws on the larger animal's nose and hold it, allowing the hunter to move in for the kill.