During Trajan's reign, the cohorts adopted a dragon standard on the order of the legion's eagle. The standard is a pole with unit markers, awards, and similar unit crests and a fixed dragon or eagle on top. Starting in 175CE with the induction of the Sarmatians into the Roman army, the dragonhead standard came into use. This was a metal dragon head with a cloth windsock for a tail that looked a great deal like Chinese Dragon kites. The color of the windsock was purple when an emperor was in direct command of the unit, but the sock may well have been white or some other color when the emperor was not in direct command. By the end of the Roman period, most cavalry units were carrying the dragonhead standard in imitation of the Sarmatian numerii.