Original: History Akershus became a fief in the 16th century , and then also included the current counties of Hedmark , Oppland , Buskerud and Oslo , as well as the municipalities of Askim , Eidsberg and Trøgstad in the county of Østfold .
Simplified: History Akershus became a fief in the 16th century . It also included municipalities of Askim , Eidsberg and Trøgstad in the county of Østfold .