Scythians can best be described as a mixture of Yamnaya-related ancestry and East Asian/north Siberian elements.
https://eurogenes.blogspot.com/2017/03/genetic-origins-and-legacy-of-scythians.html?m=1
Cimmerians, Scythians and Sarmatians came from…
Apparently they all came from the eastern Pontic-Caspian steppe.
https://eurogenes.blogspot.com/2018/10/cimmerians-scythians-and-sarmatians.html?m=1