Formerly a province of Halogaland, Agder was conquered by the Empire of Videssos during the reign of Avtokrator Stavrakios. When the Khamorth invaded the Videssian Empire, Agder was separated from Videssos and became an independent Kingdom still ruled by Videssian people.

Agder was a peninsula that jutted out into the northern sea. It was bordered by Halogaland to the north and Thatagush to the south. Pardraya lay to the west. Agder managed to expand its borders significantly since its original inception.

Ruled by Videssians,the people of Agder maintained Videssian customs, though they borrowed certain customs from the Halogai, as well. They still worshipped Phos, though their Balancer theology (shared with Thatagush and Khatrish) was considered heresy by ecumenical synod of Videssos the city.