Nicene and Post-Nicene Fathers, Ser. II, Vol I:
The Life of Constantine with Orations of Constantine and Eusebius.: Chapter VI

Chapter VI.—Conquest of the Sarmatians, consequent on the Rebellion of their Slaves.

With respect to the Sarmatians, God himself brought them beneath the rule of Constantine, and subdued a nation swelling with barbaric pride in the following manner. Being attacked by the Scythians, they had entrusted their slaves with arms, in order to repel the enemy. These slaves first overcame the invaders and then, turning their weapons against their masters, drove them all from their native land. The expelled Sarmatians found that their only hope of safety was in Constantine’s protection: and he, whose familiar habit it was to save men’s lives, received them all within the confines of the Roman empire. 3312 Those who were capable of serving he incorporated with his own troops: to the rest he allotted lands to cultivate for their own support: so that they themselves acknowledged that their past misfortune had produced a happy result, in that they now enjoyed Roman liberty in place of savage barbarism. In this manner God added to his dominions many and various barbaric tribes.

Footnotes

To the number of 300,000, according to Anonymus Valesianus. This was in the year 334.