The Marpesian March was an area of the Oceana-Marpesiate that lay on the border between the Kingdom of Oceana and the Kingdom of Marpesia during the Middle Ages. The March began as a small part of the Kingdom of Oceana's territory north of Donnoir, but as the Oceanan Kingdom gradually encroached upon Marpesia, it encompassed an area of land stretching from Brathsund to Der.

The March was initially ruled over by a number of marquises, who held certain rights granted to them by the Oceanan King due to their position as the first line of defence against the Marpesians. However, after this proved increasingly ineffective during the reign of King Dicotome I, the March was organised into three separate regions - the West March, the Clutha March, and the Dermarch - and the position of Warden was created for each. The Wardens oversaw the marquises, and were responsible for the organisation of defence and security. Under the reign of King Lemmattus, the position of Lord Warden of the March was created in order to further secure the March.

During this period, the March was looked upon by many Oceanans as a place of lawlessness and danger. The March was often only weakly under Oceanan control, and raider families known as Jacks of the March often looted farms, towns and each other's territories.

After King Morpheus I inherited the Oceanan throne and joined the crowns of Oceana and Marpesia, there was little need for border security, and the positions of Lord Warden and the three subordinate Wardens were abolished.