These were reconstructions of terms such as Achaemenids (Xwaehaex) which was derived from the Old Persian "Hakhâmanîshîyâ" (The letter X in context of Iranic languages are usually pronounced "-Kh"), and from there follows the linguistic theorems of reconstruction, either using Ossetian, Khotanese Saka or PIE as peripheries of reference.

One problem is that these words come from a preview coming from some years ago, so it's a bit difficult to track down the original scholarship of Angadil and Jurchen_Fury (JF wrote the text in question; the man possesses considerable skills as far as linguistics are concerned, but it's been a long time since); this was presumably before we had acquired a substantial amount of data on Khotanese Saka. I am willing to bet that much of the previous scholarship was based upon the findings of J.P. Mallory and that of the late Janos Harmatta and William Tarn.

There is one occasion where the Persians truly extended beyond the river Jaxartes deep into the lands of the "Haoma-drinking Scythians", and this occasion took place during the campaigns of Darius I The Great. This can be alluded by "300 years ago", and a certain "duke" of a city called Mjuwk of Dzin. If we make a rather simplistic abstraction of this name, we'd end up with "Mogha". This is an interesting finding, because in the time between the first centuries BCE and CE, we come across the so-called Taxila copper-plate, otherwise known as the "Moga-inscriptions"; written on the orders of a fellow known as the founder of the Indo-Scythian hegemony, Maues (Gr. ΒΑΣΙΛΕΩΣ ΒΑΣΙΛΕΩΝ ΜΕΓΑΛΟΥ ΜΑΥΟΥ). In the plate, which was written in the Kharoshthi script, his name is referred to as "Moga". One might get tempted to throw in the Kamboja into the general picture as these areas were part of their original habitat, but for this time, let us exclude them for the sake of keeping this simple.

What is then this "Dzin"? It might be difficult to tell, but at the same time we are given another clue; Tsyuw. This is a "Scythianized" projection of the Xiyu-states which were located at the western mouth of the Tarim Basin. This is further alluded by the mention of the "Togar", which could be none other than the Tocharians of the Graeco-Roman classical fame (Tokharioi/Tocharii). It must be noted that the text features plenty of improvized Chinese manipulated to sound like as if they were spoken by a Saka (D'ad-Ngiwat-Tieg; this is an earlier reference to the Da Yuezhi who are identifiable as the Tocharians as a whole, according to J.P. Mallory), which of course is deployed excellenty as a narration technique (Albeit hard to track down ultimately). With respect to that "Mjuwk" is clearly Indo-European, in that we find Iranic cognates to the name, "Dzin" must therefore reference to something else than "Chi'n" (China).

Dzin... Honestly? The only thing which pops up in my head is the Tajik city of Dushanbe, which granted, is located comfortably close to the geography relevant to the topic, but I can't say for sure. Now there are some archaeological findings that places Dushanbe as a historical site as far back as the 5th century BCE, probably a Soghdian village or outpost, but this is conjecture spread as thinly as a playing card, if intellectual honesty may be allowed. However it may be reinforced by the military doctrines left to us by Darius I The Great in the Bâgâstânâ/Behistun and Naqsh-î-Rustam inscriptions, where the defeat of his enemies are enumerated.

Therefore, this "Moga" which may have been Darius' lieutenant (Darius had, according to the Behistun inscription several generals dedicated to the task of quashing rebellions following the Gaumâta/Smerdis/"False Smerdis" conspiracy), who acted as the extended arm of the Achaemenids, therefore the allusion to "Mjuwk" ruling the "four corners of the world", and this is yet another Achaemenid concept, presumably coined by the Persian ruler, Cyrus II The Great in his Babylonian cylinder commemorating the capture of Babylon.

Let's see what else we can throw into the mix...

We may have reached the conclusion of "Dzin" being "China" if the reconstruction read "Zhin", but it does not; Dzin on the other hand emphasizes a brief pause, which may be read "D'zin", and from blossom into "Dusan"/"Dushan"/"Duzan". Eventually, in New Persian, the form of "Dushanbe" literally means "Monday" (In the sense of "Second day", following "First day"/Sunday and "Day"/Saturday in the modern Iranian calendar)

Let's get a bit relaxed and have some fun with the subject: In Middle Persian/Pahlavîg... This one is going to make anyone laugh out loud but "du/dôg/dô" (Two) - "san/shan" (Hemp) - ba/be (Plural marker for preceeding noun; think English -s suffix) exactly means "Two hemps". We are talking hemp, maybe as in the plant itself: Sahdanag means precisely "Seed of hemp" which of course is a cognate to "shan/san". We are talking about Cannabis. Ganja. Reefer. Weed.

Why is this so interesting? Well, besides the fact that Afghanistan today produces tons of this good shit, and besides that Tadjikistan (Where Dushanbe is located as its capital city) apparently is a gigantic drug disposal site in Central Asia, right to the north of this area, the Saka Haumavarga presumably roamed; their very titular name designates consumption of ephedra, a plant otherwise known as "Haumâ/Haomâ" which is an entoxicating, hallucinogen beverage, which is mentioned in Avestan sources such as the hymns of Zoroaster (Gâthâs). This is what we'd call historical irony. It is quite likely that Dzin might be a reconstruction of this dwelling of "Two hemps".

The legacy of Scythians frolicking in fermented beverages and drugs is not only restricted to the "Eastern Scythians"; we meet such patterns in the Scythic allies of the Pontic ruler, Mithridates VI Eupator, where Scythian sages would prepare the famed herbal mixtures (As he was desensitizing himself against poisons, a concept we today know as mithridatism). The nomads clearly knew how to have fun.

Pure coincidence? Maybe. Dushanbe is a modern name, and my connotation of it to "Dzin" is loose, solely based on the few archaeological remains found in the vicinity of the city and the utter convenience of its location as a Soghdian outpost. It goes however to show that with a few clues, you can with some inquisition reach certain approximations, reductions and from there a conclusion which does not deviate from the established parameters.

I hope this helped answering your question.