I would first like to point out that the premise of the question is flawed. Russia did end up conquering and incorporating Mongolia, in a sense at least, because Mongolia was a Soviet satellite state from 1924 to 1992. But that, I suspect, is not what you're asking about. Why did Russia not conquer Mongolia during its drive for the Pacific in the 17th century? The answer, of course, is Manchuria. Well, not just Manchuria, but the Manchu Qing Dynasty, which, by the time the Russians first encountered it in 1650, had effectively conquered most of China. The Qing state did not have a pre-ordained, long-term plan of conquest in Mongolia, but it did have significant strategic interests there that eventually drew it into a longer-term relationship with the region that lasted until the dynasty's fall.

The first thing to say here is that the Russians' 17th-century expansion into eastern Siberia did not involve much movement into regions dominated by established state entities or nomadic federations, the westernmost of which, the Khanate of Sibir on the eastern side of the Urals, fell to the Russians in 1580. From there on out, the Russians were largely expanding into regions where there was relatively little in terms of organised entities able to resist their advance. However, the resources of the Russian state were also greatly limited, and the colouring-in of the map obscures how the Russians actually controlled very little within their nominal borders. Instead, they merely established a series of forts and outposts along strategic positions, held a loose-rein relationship with ostensibly subjugated tribes, and employed accommodation as well as force in order to maintain stability in a region that traditionally did not have particularly substantial political organisation. Mongolia, however, was home to relatively substantial nomadic federations, notably the four Khalkha khanates, which presented a much greater obstacle. Moreover, the Russo-Qing border conflicts from 1650 to 1689 saw the Qing quite decisively victorious, as the Manchus and their Korean allies were able to deploy far more resources to the theatre than the Russians could ever hope to. That is not to say that the Russians avoided engagement with the Mongols, far from it: tribes like the Oyirads, for example, traded with Russia in order to obtain weapons and other goods. But a drive southwards into Mongolia was unlikely to succeed in any case.

Indeed, the Mongols had some success in offensives against Russia, such as in 1688, when Khalkha tribes swept north and besieged the Russians in Selenginsk, which they would not relieve until the spring of 1689. The occasion for this was the invasion of eastern Mongolia by the Zunghar Khanate, an Oyirad-led formation based in western Mongolia whose leader, Galdan, saw himself as appointed by the Dalai Lama to reunite the Mongol tribes and enforce the Gelug sect's orthodoxy in the region. The attack on Selenginsk by the fleeing Khalkhas disrupted the planned peace negotiations between the Russians and the Qing over outer Manchuria, which resumed after the fort was reclaimed. On the surface, the terms of the Treaty of Nerchinsk, which emerged out of those negotiations, are quite basic: provisions for border markers, stipulations regarding refugees, and terms where trade to China could be conducted by Russian caravans. But the trade stipulation was key. By allowing Russia to sell a portion of its Siberian furs to China at marked-up prices, the Qing gained a critical piece of economic leverage over its competitor, as any act that might be seen as breaking the peace, such as interference in the Qing-Zunghar conflict, could lead to the Russians forfeiting this lucrative trade opportunity. Galdan would receive no help from Russia in the coming years.

The Qing counterattack against the Zunghars drove them out of eastern Mongolia, which by the end of the 1690s was under Qing control, the Khalkha khans having submitted to Qing overlordship. This would prove to be the start of a prolonged period of conflict between the Russians, the Qing and the Zunghars over control of parts of Inner Eurasia, which eventually the Qing won, establishing suzerainty over Tibet in 1720 and conquering the Zunghar Khanate outright in 1757. But the economic leverage over Russia that the Qing had gained through the Nerchinsk treaty meant that Russia was unlikely to win the contest for Mongolia specifically. Although some terms were modified in the 1727 Treaty of Kiakhta, the basic principle remained: Russia was in effect being paid to stay out of Mongolia. The border trade persisted until into the 19th century, and remained a lucrative disincentive against drastic action against the Qing.

Of course, the Russians did, after 1858, take a much more heavy-handed approach to the Qing, pressing their interests on both Manchuria and eastern Turkestan at the height of the Taiping War and the Muslim revolts in Xinjiang. However, Mongolia was not in the picture, not least because there was relatively little strategic value to be gained out of it. Expansion into Manchuria offered access to the Pacific through Vladivostok. Expansion into settled Turkestan relieved pressure on Russia's fortified frontier and also enabled more direct access to markets in Xinjiang. But invading Mongolia would achieve little. It would not ease access to markets in China proper, nor would it provide much of a military advantage at the global level. And it must be said here that conquests were extremely expensive and slow to plan. Assembling the necessary supplies and, crucially, pack animals for a military expedition in Turkestan could take over a year, and this was where most of Russia's military resources east of the Urals were already concentrated. To establish the infrastructure for more aggressive action in Mongolia would be an immense expenditure of resources which would see little return.

Sources, Notes and References

• Peter C. Perdue, China Marches West: The Qing Conquest of Central Eurasia (2005)

• Alexander Morrison, "‘Nechto eroticheskoe’, ‘courir après l'ombre’? – logistical imperatives and the fall of Tashkent, 1859–1865", Central Asian Survey, 33:2 (2014), 153-169

Hey there,

Just to let you know, your question is fine, and we're letting it stand. However, you should be aware that questions framed as 'Why didn't X do Y' relatively often don't get an answer that meets our standards (in our experience as moderators). There are a few reasons for this. Firstly, it often can be difficult to prove the counterfactual: historians know much more about what happened than what might have happened. Secondly, 'why didn't X do Y' questions are sometimes phrased in an ahistorical way. It's worth remembering that people in the past couldn't see into the future, and they generally didn't have all the information we now have about their situations; things that look obvious now didn't necessarily look that way at the time.

If you end up not getting a response after a day or two, consider asking a new question focusing instead on why what happened did happen (rather than why what didn't happen didn't happen) - this kind of question is more likely to get a response in our experience. Hope this helps!