I wonder whether the trade deficit European nations sustained when trading with China has been resolved? In OTL Great Britain and Spain fought many conflicts in the new world which disrupted silver production. Silver was prioritized for trade with China, which caused European economies to shrink.
ITTL, Mexico, the Shimazu and the Romans have a near monopoly on the silver market. Since they have consolidated their control over the Gangetic plain, perhaps GB will begin cultivating opium earlier to reduce the deficit with China?
I think I went on a rant in this thread about silver trade to China. I don't remember the specifics, but to summarize: silver is not necessary for trade with China, it's just the most convenient mutually agreeable medium of exchange. What makes silver into a bad trade good is because it's heavy. Throwing a bunch of precious metals onto a boat means it's going to be slow or even sink if you fill it up too much. The trade goods Europeans brought back from China such as tea, silk, porcelain, and spices are comparatively much lighter. Just like the Venetian trade for spices in the Levant this results in more trade value coming from China then going to it. This is not in and of itself a problem, because European traders only have that silver to trade. So the trade value that they bring to China, can only be exchanged for enough goods that that silver can buy. So since silver is heavy, it can't really buy all that much since a trade ship is limited by its tonnage. Europeans still turned significance profit selling goods back in Europe.
what opium did was allow for a better weight to value ratio. Suddenly 100 tons of cargo could buy you much more tonnage of Chinese goods and thus turn a greater profit.
The only reason that silver was problematic was that it was also used as a currency, which led to a bullion famine in Europe for silver that dramatically increased its price. As a result, inflation occurred since the individual silver coins were now more valuable. This, and other silver bullion famines such as the one in the 15th century as well as gluts on the discover of Potosi, led directly to abolition of the silver standard in Europe. Gold became the backer of currency in Europe due to its greater stability over the centuries. This relegated silver coinage to simply an expression of a value of gold, rather than an expression of a value of silver. None of this is an actual problem. Not until the 19th century.
When trade exploded in that period demand for Chinese goods vastly outstripped actual ability of Europeans to pay for it. This only occurred because paradoxically Chinese products became more accessible by advances in trade technology, culture, and infrastructure over the course of the 18th century.
Now it was impossible for Europeans to buy the Chinese products they needed and ONLY at this point were alternatives necessary rather than just a grumbling wish of the merchant class. This is when Opium became the trade alternative. Only when these events come to pass will we see some sort of Opium trade to China. Silver will continue to reach Europe until its supply becomes wholly consumed by trade with China.
Do they really need an external stimulus? Perhaps a charismatic figure will simply convince them that the centralization of power brings rich spoils and new lands like how Temujin united the warring Mongol clans.
Why would unification necessarily come with centralization of power? Autonomy can be retained so long as they give lip service to a central monarch.
Funnily enough I was doing some reading on Alcoholism in Russia and it's depressing. Cheap Vodka has been used as a tool of social control by the Russian state since Ivan the Great. The Tsars put into place an alcohol monopoly in the country, taking away the previous ability of the peasants to distill their own vodka. They expanded the industry dramatically and flooded their own market with cheap alcohol. In doing so, they created a tremendously valuable revenue stream for the Russian State and ensured that their own peasantry would be too drunk to rebel. Additionally they created a cycle of addiction and dependence which kept the common Russian impoverished. Come the time of Catherine the Great this monopoly was so valuable that favoured court members were given Vodka plants to manage rather than grants of land. The communists were actually a prohibitionist party and smashed all the Vodka they could find until Stalin ruined it by reopening the plants and bringing the levels of addiction to a whole other level.
ITTL there is no unified Russia to impose a state monopoly on alcohol production. Russia is a broken state in competition and in many cases is nowhere near as authoritarian. This will have tremendous effects on Russian culture and government, as it would reduce poverty and increase political activity of the lower and merchant classes. I don't know how much, if at all, B444 would have anticipated this sort of thing but it's an interesting element of TTL's politics and culture regardless.