Another set of five knights! These are the aspiring rookies, the young and the impatient. They have only just joined and must prove themselves to the Order of the Black Tower. This is best represented by the cream colour in their uniform as opposed to the black the knights of the Order usually wear.
But there are a bunch of smaller hints as well, such as their unbarded mounts, the unadorned lance poles, open-faced helmets (as opposed to closed) and so on.
Another obvious sign that these knights are initiates is found on their shields, bearing not the Black Tower, but instead the Chains – bound to prove their worth still, in hope of one day earning the Black.