Unlikely, and a description which probably originates in misreading the texts.
Pro-Turkic, quite fairly, because the Turks were of mixed Mongolian and Siberian tribal origins, so for the presumably proto-Mongolian Xiong Nu to be considered proto-Turkic is quite in order.
The Xiong Nu, under pressure from the Han, recoiled west, and uprooted the Tokharian culture around the Tarim Basin. The Tokharians seem to have split into three groups: one took refuge in the Tibetan highlands, one joined their tormentors and were absorbed, and the last, the largest group, fled westward, fell upon the people of the Oxus and Jaxartes basins, the Scythians, and drove them south and west.
The Scythians themselves were of mixed ethnicity.
It is possible that this succession of events, occurring in quick step, confuses many of us. However, the Xiong Nu were not the Scythians, nor, originally, the Tocharians, the Tocharians in part joined the Xiong Nu, after being defeated by them, and the main branch of the Tocharians drove out the Scythians and probably themselves mixed the ethnicity of the steppes further. These Tocharians, as their existing mummies still show, were white-skinned blondes; their later coins, when they ruled as the Kushanas in Afghanistan and northern India, showed them to be long-nosed.
In case this confused things further, imagine the tribes and peoples to be segments running from east to west:
- Han, later formed the Qin empire under Shih Huang;
- Xiong Nu;
- Mingled Xiong Nu and Tocharian;
- Tocharian;
- (possibly) Tocharian-Scythian admixture;
- Scythian;
The Tocharian language, incidentally, unlike the language of the Scythians and the Iranians or the Indo-Aryans, was part of the Indo-European branch of Proto-Indo-European, closer to Greek, Latin, German, Celtic than to Iranian, east Iranian or Old Indo-Aryan (Sanskrit).
