Complex sentence: Although "Riksmålsforbundet" was founded in 1907 by the poet Bjørnstjerne Bjørnson, the efforts to organize in support of riksmål goes back to 1899, and served as opposition to efforts by those Norwegians who had organized to promote landsmål as the single language for the country.
Split into simpler sentences: Although "Riksmålsforbundet" was founded in 1907 by poet Bjørnstjerne Bjørnson, the efforts to organize in support of riksmål dates back to 1899. It served as opposition to efforts by Norwegians who were organized to promote landsmål as the single language for the country.