Complex sentence: The history of Norwegian state-operated naval forces is long, and goes back to the leidang which was first established by King Håkon the Good at the Gulating in 955, although variants of the Leidang had at that time already existed for hundreds of years.
Split into simpler sentences: The history of Norwegian state-operated naval forces is long, and goes back to the leidang which was first established by King Håkon the Good at the Gulating in year 955. Although variants of the Leidang had at that time already existed for hundreds of years.