I dunno -- the term Scythians I look upon with extreme distrust -- it seems to be a generic term the Persians, Greeks and Romans used for 'barbarians to their north-east and seems to have included at various times Germanics, Slavs, Turkics and Indo-Irani groups. It seems to have been used as a generic term for 'barbarians'
"...the Yuezhi (Yüeh-chih in Wade-Giles), an Indo-European-speaking nomadic people who had relocated from China's present-day Gansu Province as a result of their earlier defeat by the Xiongnu."
There is the Gansu area and Indo-European speaking people again.