It is named after the Dalmatae, an Illyrian-speaking tribe that inhabited the Adriatic coastal mountain range of the eponymous Dalmatia.

The ancient geographer Strabo describes these mountains as extremely rugged, and the Dalmatae as backward and warlike.

According to Holder, a total of 12 Cohortes Delmatarum appear to have been raised after the suppression of the Illyrian revolt in two series, of 7 and 5 respectively.

Holder suggests that the regiment may have taken part in the Roman invasion of Britain (43) or the suppression of the revolt of Boudicca (61), but there is no evidence.

From the locations of their votive or funerary stones, it can be deduced that at least 4 were central/southern Italians: from Aquino, Beneventum, the city of Rome (c. 120), and Tusculum.