The main problem with the alleged influence of the preferred intooxicants on the adoption of the religion in Western and Central Asia is that it completely ignores the timeline of the development of hard liquors and is generally not in line with the tenets of Islam, either. It looks like a modern invention based on the projection of the characteristics of people living in the aforementioned region today onto the realities of 9th-12th century, what, as one might assume, does not instill faith into academic competence of its author to say the least.

The idea that people have chosen their religion based on the propensity to drink alcohol or consume hashish, especially in the context of the Eastern Europe is likely to be based on the Tale of Bygone Years that contains the following passage, speaking of the Muslim Bulgarians who came before Prince Vladimir, presenting him their faith. It goes as follows:

Придоша Болъгаръı вѣръı Бохъмичѣ. гл҃ще ӕко тъı кнѧзь єси мудръ и смъıсленъ. не вѣсı закона. но вѣруи в законъ нашь и поклонисѧ Бохъмиту. и реч̑ Володимеръ како єсть вѣра ваша. ѡни же рѣша вѣруємъ Бу҃. а Бохмитъ нъı оучить гл҃ѧ. ѡбрѣзати оудъı таинъıӕ и свининъı не ӕсти, вина не пити, а по смр҃ти же реч̑. со женами похоть творити блоуднүю. дасть Бохмитъ комуждо по семидесѧт женъ краснъıхъ . исбереть єдину красну. и всѣх̑ красоту възложить на єдину. та будеть ємү жена. иде же реч̑ достоить блудъ творити всѧкъ на семь свѣтѣ, аще буде кто оубогъ то и томо. и ина многа лесть єӕже нѣ льзѣ псати срама рад̑ . Володимеръ же слоушаше ихъ, бѣ бо самъ любѧ женъı. и блуженьє многоє, послушаше сладко. но се єму бѣ нелюбо обрѣзаньє оудовъ и ѡ неӕденьи мѧсъ свинъıхъ а ѡ питьи ѡтинудь. рька Руси єсть весельє питьє . не можемъ бес того бъıти.

And then came Bulgarians of Mohammedan faith. They said: "Oh, prince, you are wise and smart, but you do not uphold the law, so accept our laws and bow to Mohammad'. And Vladimir asked what was their faith. And they replied: 'We believe in God and Mohammad teaches us this: do a circumcision, do not eat pork and do not drink wine, but after death, you may be merry with women. Mohammad will take seventy women, choose one, give her the beauty of all the seventy and give you that one as a wife. And you can be seek pleasures as those who are poor in this world, will be poor in the other. And they also said other lied that is shameful even to write about. Vladimir liked women and pleasures, so he listened to them eagerly, but he didn't like the circumcision and abstinence from pork. And about drinking he said: Rus is merry when it drinks, we can't do without it'.

This text is quite hard to take literally, however, as the chronicle itself has been written roughly 240 years after the adoption of Christianity by Prince Vladimir and the subsequent baptism of Kievan Rus, with the earliest known copy being written only in late 14th century. Furthermore, chapter opened by the quote above is generally a presentation of Eastern (Orthodox) Christianity as the only 'true' faith by pointing various shortcomings of other confessions mentioned there (Western Christianity, Judaism and Islam).

Now, let's move to the factual evidence. First and foremost, if we want to precisely adhere to the terms used, we need to note that the invention of vodka and the adoption of Christianity in what is now Western Russia is separated by almost nine centuries. What is called 'vodka' today is, unlike simple distillates, a mixture of pure consumable ethanol created by fermentation and distillation (with 'pure' meaning a point of azeotropy rather than 100% purity, but it is close enough) and diluted by water so that the final product contains 36-42% of alcohol by volume, depending on the local practices, traditions and regulations. Such a product could have, of course, been produced only with highly advanced industrial processes and equipment. And indeed, vodka as we know it has been introduced in mid-19th century, with Michael Reutern, Minister of Finances in the council of Alexander II introduced the '40% ABV standard' to make the excise and tariff calculation easier. This is often incorrectly attributed to Dimitri Mendeleyev, possibly because one of his early papers is titled 'About mixing of alcohol and water' (but it is actually dedicated to the aforementioned phenomenon of azeotropy) and the fact that he was appointed Director of the Measurements and Weight Office (an equivalent to modern ANSI and equivalent institutions) that was overseeing the application of various standards, including the one introduced by Reutern. The fact that almost anyone with modicum of general education heard of Mendeleyev as he is an author of the Table of Elements, while Reutern is a definitely obscure character might also be a likely culprit.

Of course, if we do not want to be too nitpickish, we might assume that the term 'vodka' was intended to mean all hard liquors. But this does not make the theory much more plausible, as it is still few centuries off the mark. Strong, distilled drinks that could have contained at least 25-30% alcohol by volume were introduced only in the very late Middle Ages and their production took off in 16th century. Although the procedure of distillation was known by Greeks around 1st-2nd century AD, there is no indication that it was used to produce alcoholic drinks. This knowledge was later developed by Arabs and Latins, but the first distilled alcohol is dated back to late 11th century and it is still a drink made of wine that has been distilled to increase its alcohol content (essentially making it brandy). This method was prevalent in Europe until 15th century, making it to Rus only in 1380s, when it has been brought there by Italian merchants. A grain distillate must have been created somewhere in 15th century (possibly after the attempts to distill beer), as one of the first sources mentioning it is the Treatise of Two Sarmatias written by Polish chronicler Maciej Miechowita and published in 1517, where author states that 'people of Muscovy use oats to make burnt liquid in the vein of spiritus and drink it to save themselves from cold' (with the word 'spiritus' being a shortening of the expression 'spiritus vini', or 'spirit of wine', a common Latin name for early brandy, giving name to modern 'spirits'). In addition, Kievan Rus was located relatively far to the north, in the strictly continental climatic zone that made viniculture difficult and contributing to scarcity of wine that was considered a rare, imported commodity. Thus, it is conjectured that until late Middle Ages, Russians were consuming primarily beer, kvas and mead, not unlike Northern Europeans.

Another important problem is that the location of the alleged 'Hashish-Vodka line' is never specified and thus we can hardly discuss it in the context of the colonization of Asia. It cannot be synonymous with the divide between present ethnicities of the inhabitants of the region (European/Asiatic), as the Siberia is today a part of Russian Federation and is populated in large part by Slavs, but this was not the case until fairly recently. Russians were largely not present beyond Ural Mountain until the late 16th century and the mass colonization of Asian part of the Russian Empire was not really conducted until early 19th century. Until then, the regions was populated chiefly by Siberian, Altaic and East Asian indigenous people.

Now, even if we attempted to draw such a line, it would be definitely not anywhere close to straight. Without chronological boundaries one would find it hard to find any solid border between people commonly using alcohol and the followers of abstinence (not even necessarily utilizing hashish). For example, in 15th century Europe, you have the Arab Northern Africa, Turkic Asia Minor and Middle East, Christian northern Mediterranean region and the Christian Northern Europe, with the Muslim Crimean Khanate sandwiched between the latter two in the area north of Black Sea. And it is not that Crimean Tatars suddenly appeared in that region, as they were present since the times of Golden Horde, when they joined other Asiatic peoples residing there, chiefly members of so-called Kipchak-Polovets Confederation that were present there from Early Middle Ages. Furthermore, the division is far less pronounced in Ottoman Empire, where the Turks, predominantly those of more means, adopted the local customs of wine drinking, while the hashish was consumed mostly by the poor, due to affordable price. Evliya Celebi notes in his Seyahatnâme that in during his visit in Constantinople in the mid-17th century there were more that 1000 places where people could have buy alcohol, chiefly wine, raki and boza. Even though accuracy of the book is disputed, it nevertheless shows that alcohol was more common in the northern part of the Ottoman Empire, to large extent due to the fact that it was a region where various cultures interacted and Constantinople was a cultural melting pot, like most major trading hubs.