The original five teams that joined the NHL in 1917 formed the foundation of modern hockey. They were the Montreal Canadiens, Toronto Maple Leafs, Ottawa Senators, Quebec Bulldogs, and Montreal Wanderers. These teams were all part of the National Hockey Association (NHA), which was the predecessor to the NHL. The teams decided to join the NHL in order to gain more control over their own destiny and to ensure that the sport of hockey would continue to thrive and grow. The NHL also offered a more structured league with better financial stability, which appealed to the teams. Ultimately, the teams decided to join the NHL to ensure the future of the sport, and the league has become one of the most successful sports leagues in the world.