The Roxolani, or “bright Alans” are a Sarmatian people who are, in their turn, a Scythian-speaking collection of tribes. As might be expected of steppe nomads they are fine horsemen, ruthless warriors, and merciless towards their enemies. Like all the steppe nomads, there a many forces drawing them south and east away from the steppes. The prospect of easy pickings from soft and sedentary civilized people is foremost among these reasons. The harsh reality of steppe life and tribal politics is that tribes have to be aggressive, or be crushed by other steppe tribes.
Historically, the Roxolani were sometimes allies of the Dacians, and fought alongside them against the Romans. There are Roman claims that Legio III Gallica and its supporting auxiliaries destroyed a 9,000-strong raiding force of Roxolani in 69 AD. This sounds more like the destruction of a complete cavalry army; the Roxolani took their revenge a generation later by wiping out Legio XXI Rapax. The Romans certainly came to consider the Roxolani a threat and, aside from using some as auxiliaries, fortified their frontiers against them.