Although originally drafted from the various Gallic tribes, this unit were apparently bolstered by a large contingent of Picentine horsemen from the Adriatic region of central Italy. They are attested in Upper Germany on Diplomata issued in AD74 and 82. The only record of this unit in Britain is an altar dedicated by the prefect Candidus, from the ruins of the Severan bathhouse at Malton (Derventio). The altarstone may have been relocated from a previous structure on the site. The later history of the unit is unknown.

Evidence for the presence of Ala Gallorum Picentiana in Britain

1. Burn 100; CIL XVI.65 military diploma dated: July 17th AD122.
2. Cil Vii.1195 privilegia militvm; dated: September 16th AD124.
3. Derventio (Malton, North Yorkshire; Britannia ii, 1971, p.291, no.9)