[2] This occurs in a letter written by the co-emperors Honorius and Theodosius II to Gaudentius, the vicarius Africae, in 409, and preserved in the Codex Theodosianus.

Baradez also postulated a pulse of construction during the reign of Gordian III in the 3rd century, and finally abandonment of the Fossatum in 430–440 after the Vandal invasion.

[5] Having been built in an arid region of strong winds and blowing sand, the Fossatum quickly eroded and only traces remain.

However, the full extent of the Fossatum was not known until after World War II, when the use of aerial photography to locate archaeological sites was pursued by Col. Jean Baradez.

In the more peaceful modern era, the use of the Fossatum as a customs and migration control has been brought to the fore, suggested by inscriptions at Zaraï giving long lists of products and tariffs.

[15] There also appears to be a 20 km (12 mi) fossatum at Bou Regreg in Morocco although this would not have been within the scope of the proclamation of the Codex Theodosianus because at that time the province was not in Africa, administratively speaking.