The NHL was founded on November 26, 1917. It consisted of 5 teams but it was not until 1942 when the “Original 6 Era” began that the NHL became a worldwide phenomenon. The Original 6 were the Boston Bruins, Chicago Black Hawks, Detroit Red Wings, Montreal Canadiens, New York Rangers and Toronto Maple Leafs, who played each other time and time again until in 1967 when the NHL had an expansion of 6 more teams. As time goes on, temas are added, removed, and relocated. Check out this link for a full timeline of the NHL. Without the start of the original 6, the NHL would not be what it is today.
Sources: https://www.thecanadianencyclopedia.ca/en/article/the-birth-of-the-national-hockey-league-feature/
https://www.nhl.com/news/nhl-expansion-history/c-281005106
Deeper into Hockey 