The real "Tocharians" were limited to a very specific area North East of the Tarim basin, and even they spoke Sogdian as the dominating language. When I do the in-depth overhaul of Central Asia, I plan to give them their due share in that area, as to each original people of the Tarim basin. The Iranian people who lived in pre-Islamic Transoxiane, who had a brilliant civilization, imposed their language as the lingua franca from China to Persia were actually the Sogdians - even becoming major factors on the political scenes of both the Tang and the Abbasid Empires. So indeed for the release of the Eastern map, the people inhabiting that are ought to be the Sogdians. You still see their legacy in modern times as the majority of city-dwellers of pre-Russian Central Asia were Persian-speakers "Tajiks", actually descendant of the Sogdians who switched their Iranian language to the mainstream Persian through the times to resist total acculturation during Islamic times.
For more background on that area, rather than inviting you to read... I would invite you to play a Sogdian ruler in HIP, as they have a good expert of the area who modelled the Sogdian culture quite well (including a very interesting music package for them, I learned quite a lot myself through it)