 Whereas the internal organisation of the "auxilia" had previously been left up to their commanders, in the early empire they were organised into standardised units known as "turmae" (for cavalry "alae") and "centuriae" (for infantry "cohortes").Although never becoming as standardised in their equipment as the legions, and often retaining some national flavour, the size of the units at least was standardised to some degree.Cavalry were formed into either an "ala quingenaria" of 512 horsemen, or an "ala millaria" of 1,000 horsemen.