Complex sentence: In the 970s, Haakon Sigurdsson, Jarl of Lade, became the most powerful man in Norway, at first supported by Harald Bluetooth of Denmark and paying tribute to him--though the two later fell out over religious matters.
Split into simpler sentences: In the 970s Haakon Sigurdsson, Jarl of Lade, became the most powerful man in Norway. At first supported by Harald Bluetooth of Denmark and paying tribute to him the two later fell out over religious matters.