In Stalingrad, one of Vasily Grossman’s two epic novels centred on the second world war’s most destructive battle, a particularly powerful passage depicts exhausted Soviet soldiers arriving at the River Volga and washing themselves in its waters. “This mass baptism before the terrible battle for freedom . . . may have been as fateful a moment in the country’s history as the mass baptism carried out in Kiev a thousand years earlier, on the banks of the Dnieper,” Grossman wrote.

Kyiv is now the capital of Ukraine, but the intense religious symbolism of Grossman’s scene captures the way in which Russians down the centuries have thought of the Volga as embodying their nation’s identity and fate. It flows for more than 3,500km from its source north-west of Moscow to the Caspian Sea. It has served both as protector of “Mother Russia” against foreign enemies and as a symbol of freedom for those, like the peasant rebels of tsarist times and the early communist era, who resisted an oppressive state.

Yet if the Volga stands for the Russian national spirit, it does so in complex ways. Janet M Hartley, author of The Volga: A History of Russia’s Greatest River, and Mark Galeotti, author of A Short History of Russia, each makes the point that the river came under full Russian control only after Ivan the Terrible’s conquest of the khanates of Kazan and Astrakhan in the 1550s.

This vast territorial expansion, which established Russian sway over the Volga’s entire length, gave access to the Caspian Sea and opened the road to Siberia, “marked the beginning of Russia’s transformation from being an essentially homogenous nation” to one that “came to embrace new peoples, new cultures and new religions”, Galeotti writes. The story of the Volga, like that of the tsarist empire, the Soviet Union and post-communist Russia, is inseparable from the story of the Tatars and other non-Russian peoples who share the same geographical space as their Russian neighbours.

Hartley, emeritus professor of international history at the London School of Economics, has produced a study of the Volga that is as well-researched and accessible to general readers as her much-praised 2014 book Siberia: A History of the People. “Although the Volga was never the geographical border between Asia and Europe, in many ways the middle and lower Volga does draw a line between the Christian, Russian, European west and the Islamic and Asiatic east,” she observes.

A similar thought seems to have occurred to Catherine the Great, the German-born empress who usurped the Russian throne from her husband in 1762 and toured her Volga dominions five years later. From the multi-ethnic city of Kazan she wrote to Voltaire, her French philosopher penfriend: “I am in Asia . . . there are in this town 20 diverse sets of peoples who in no way resemble each other.”

Hartley has a good eye for the significant detail. Famously, Catherine invited thousands of German colonists to settle on the Volga, where they farmed their lands in peace for almost 200 years until Josef Stalin deported them en masse to Siberia and Kazakhstan in 1941. Less well remembered is that the arrival of the Germans in Catherine’s reign prompted some 150,000 local Kalmyk inhabitants to pack up their tents and leave for their ancestral homelands on the Chinese border. Attacked by bandits and suffering from extreme weather, up to 100,000 died, Hartley estimates.

In the 19th century the upper Volga hosted the gigantic trade fair at Nizhny Novgorod, a city described by the Marquis de Custine, a French aristocrat who was hard to please in matters Russian, as “the most beautiful [town] I have beheld in Russia”. But conditions for river workers were often grim. Ilya Repin’s painting “Barge Haulers on the Volga”, which now hangs in the Russian Museum in St Petersburg, is “a wonderful example of realist painting and a compelling social critique”, says Hartley.

The Volga played a central part in the great events of 20th-century Russian history, from the civil war that followed the 1917 Bolshevik coup to the second world war. The victory at Stalingrad is a cornerstone of President Vladimir Putin’s effort to persuade Russians that they must have a strong, fortress-like state because ill-intentioned foreigners, especially to the west, lie round the corner.

Yet under the Soviet dictatorship industrial progress was achieved, as Hartley shows, “at a terrible environmental, economic and human cost”. Soviet repression of religion had long-term consequences too. In the post-communist era, there are tensions between the Russian state and the emergence in Tatarstan of a Muslim-influenced Tatar national consciousness.

Galeotti, one of the most astute political commentators on Putin and modern Russia, says the country nowadays is defined by “a mix of prickly defensiveness and an inclusive nationalist myth of a unique historical mission”. These attitudes have deep roots in the Russian past. From the Time of Troubles of the early 17th century, when the state broke down and foreign invaders swarmed into Russia, emerged “a growing national self-image as both beleaguered fortress amid a sea of enemies and also guardian of everything that was good and proper”.

The strengths of Galeotti’s relatively short book lie in the way that he sees patterns in Russian history without overdrawing parallels between distant times and the present day. In the Soviet era, more than a few western historians suggested that Russia had a predisposition to despotism originating in the “Mongol yoke”, the medieval period when the still not united Russian lands languished under the Golden Horde, the western part of the Mongol empire.

This experience supposedly cut off Russia from European civilisation, causing its rulers and people to internalise autocratic “Asiatic” practices. Galeotti rejects that argument as a “convenient myth”, proposing instead that the roots of Russian absolutism lie in the sheer difficulty of governing and collecting taxes in a country so vast, relatively poor, hard to travel around and with often undetermined frontiers.

Galeotti offers the useful insight that for all Putin’s militaristic adventurism abroad, “his regime is essentially conservative” — closest in spirit, perhaps, to that of the arch-reactionary Nicholas I, tsar from 1825 to 1855. He hints at trouble ahead for Putin, writing that since 2012 Russians have become “increasingly disenchanted, tiring of fake politics, entrenched corruption and a stagnant economy”.

Galeotti ends on what some readers may take as a surprisingly optimistic note. Thanks to the internet and international travel, Russians today are far more exposed to foreign influences than their parents and grandparents were under communism, he says. “Russia really is closer to Europe than at any point in its history . . . This is a country with a rich heritage and still vast untapped human potential.”

The Volga: A History of Russia’s Greatest River, by Janet M Hartley, Yale University Press, RRP £25/$35, 400 pages

A Short History of Russia: From the Pagans to Putin, by Mark Galeotti, Ebury Press, RRP£12.99/Hanover Square Press $27.99, 208 pages

Tony Barber is the FT’s European affairs commentator