Turkic Pechenegs Cuman-Kipchaks Slavic
In the 11th and 12th centuries, constant incursions by nomadic Turkic tribes, such as the Pechenegs and the Cuman-Kipchaks, caused a massive migration of Slavic populations to the safer, heavily forested regions of the north, and temporarily halted the expansion of the Rus' state to the south and east.