The Ice Hockey European Championships, first held in Les Avants, Switzerland in January 1910, were the precursor to the World Championships. It was the first official tournament meant for national teams, the participating nations were Great Britain, Germany, Belgium and Switzerland.[10] In North America, professional hockey was continuing to grow, the National Hockey League (NHL), the largest professional hockey league in the world, was formed in 1917.[11] The European Championships were held for five consecutive years but were not held between 1915 and 1920 due to World War I.[12]