| The king would send messengers to the Gotland national assembly, and the jarls likewise, to collect their tax. |
| The Anglo-Saxon Chronicle suggests that the Viking armies were led by jarls as often as kings. |
| These details are unclear, but titles and positions like hauldr, thegn, landmand, show mobility between the Karls and the Jarls. |
| During this period, the authority of the jarls spread south down the western sea route towards Dublin. |
| In the early period there is little clear difference between powerful jarls and the many petty kings who flourished in Denmark and Norway. |
| Later, in the eleventh century, under kings such as Harald Hardrada, the power-broking jarls were crushed. |
