And the Proto-Indo-Europeans are not the Aryans - the Aryans were a much later daughter culture in Western Afghanistan, Northern Iran and India, and probably the folks that had the beliefs outlined in the first pages of the Rig Veda.
The steppe people I am referring to are the people of the Yamnaya culture and related peoples within their horizon. The Mongols and Turks were relative late comers to the western steppes.