Possibly named after their city of origin rather than a former commander. They are recorded in Britain only on a military diploma naming men discharged from the unit during a ceremony performed at the Caerleon legionary fortress in South Wales at the beginning of the second century ad; it is possible that the regiment were stationed somewhere in Wales or south-east Britain at the time, later being moved to York. The regiment had been transferred to Noricum by 130 and was shortly thereafter increased to milliary size (i.e. one-thousand strong), remaining on station by the Danube until the end of Roman rule.

Evidence for The Ala in Britain

1. Burn 95; CIL XVI.48; military diploma, dated: January 19th ad103; from Isca Silurum (Caerleon, Glamorgan).
2. Burn 100; CIL XVI.65 military diploma dated: July 17th ad122; from Eburacum? (York, North Yorkshire).