The story
Division 2 was the second highest level of ice hockey in Sweden until 1975, when it became the third tier due to the formation of Elitserien (now called the SHL). After Allsvenskan was spun off into a separate second-tier league in 1999, Division 2 became the fourth tier.
From Wikipedia’s article on Hockeytvåan, shared under CC BY-SA 4.0.4