The earliest known units of "equites cataphractarii" are the auxiliary cavalry regiments, "Ala I Gallorum et Pannoniorum cataphractaria", stationed in Moesia Inferior and the "Ala I Ulpia contariorum", stationed in neighbouring Pannonia Inferior.
The earliest known unit of "equites cataphractarii" is the auxiliary cavalry regiment, "Ala I Gallorum et Pannoniorum cataphractaria", stationed in Moesia Inferior in the early 2nd century. Contemporary with the "ala" above was an "Ala I Ulpia contariorum", stationed in neighbouring Pannonia Inferior.