Norman Davies knows a sorry state when he sees one. A revered historian of Poland, Davies has chronicled the centuries of upheaval in his adopted land with sweep and vigor. No stranger to decline and fall, he was born in 1939 a subject of the British Empire, watched the Soviet Union implode at the height of his career and now lives in a combustible collection of states called the European Union. His new book Vanished Kingdoms (Viking; $40) is a swirling pot of gloom that makes most doomsday fare seem like tablespoons of pessimism. Davies is too deeply versed in Europe’s past to pronounce crudely about its future. Instead, he performs autopsies of the continent’s cadaver-states, and like a skilled mortician he has a gift for making them appear lifelike.

The grand tour begins with the Visigothic Kingdom of Tolosa in present-day France, and proceeds through a pageant of fairy-tale-sounding place-names: Alt Clud, Burgundia, Aragon, Litva, Byzantion, Borussia, Sabaudia, Galicia, Etruria, Rosenau, Tsernagora, Rusyn and Éire, and more prosaically, the USSR. Davies has chosen his cases less for their “teachable moments” than for the opportunities they offer to combat historical amnesia. “Today the barbarians have broken into the garden,” he writes in the introduction. “Young people have to learn in a cocoon filled with false optimism. Unlike their parents and grandparents, they grow up with very little sense of the pitiless passage of time.” If you can forgive the tetchy tone, there are wonders in this book worth discovering.

In each chapter our trusty guide first scouts out a former state’s “memory sites” on foot to see if any traces of the past live on in the local lore, reserving special fury for sanitized guidebooks and spotty municipal websites. Then he retreats to the armchair and follows up with a deep historical account of the rise and fall of the state, always from a side angle: the view of the collapsing USSR is from Estonia; the chapter on Burgundy starts improbably on the small island of Bornholm off the Danish coast, where the Burgundians may have established an early kingdom. Finally, Davies doubles back over the territory and searches for traces of the history he has told. For the Kingdom of Tolosa in Aquitaine, almost nothing remains; a few Visigothic words, “bank” and “suppa,” were smuggled into Latin, but only one exclusively Visigothic place-name in the region survives: Dieupentale. In present-day Kaliningrad, now a slice of Russia stranded between Poland and Lithuania with one of the lowest living standards on the continent, Davies finds almost no glints of the former glory of the Kingdom of Borussia, home of the ancient Prusai. Who knew that Borussia was once a powerful arm of the Hohenzollern dynasty that did the Kingdom of Brandenburg a favor when they joined to form Prussia?

The book’s most memorable chapter is devoted to a state far from Davies’s usual stomping ground: the tiny Kingdom of Etruria, carved out of Florence by Napoleon after his conquest of Italy. One of the first of his monarchical experiments, Etruria showed Napoleon’s autocratic colors and dynastic pretensions (the Bonapartes claimed descent from a noble Florentine family). After creating the kingdom, Napoleon installed an unruly band of siblings in the Pitti Palace and appointed a group of henchmen to oversee the puppet state. These included some vivid characters, such as Jean-Gabriel Eynard, financier and early marketer of blue jeans; the blood-thirsty Jacques-François de Menou, who converted to Islam and served as the governor-general of Tuscany; and the general Étienne Radet, who kidnapped the meddlesome Pope Pius VII. Needless to say, Davies finds no itinerary for would-be Bonapartist pilgrims to Florence in the Michelin Guide, though he’s happy to supply one.

What are we meant to do with all this historical detail? First, Davies proposes an Ozymandias Principle of sorts: some states simply are obliterated from the historical record, a fact that he apparently hopes will puncture the vanity of some of today’s citizens and politicians, who almost always consider their polities eternal. Second, he reminds us that long-buried nations can sometimes rise back to life unexpectedly. The Irish Republic (Éire) and the Republic of Montenegro (Tsernagora) are two of the restorations he explores. Third, and most important, Vanished Kingdoms is a chastening reminder about the vicissitudes of demography. “One of the few things that can be said for certain about Europe’s prehistoric peoples is that they all came from somewhere else,” Davies writes. “None of Europe’s modern nations are genuinely native.” The French are mostly former Germans, many modern Greeks are former Slavs and Turks, and one of the few members of the Royal Family who could trace her line back to the Norman Conquest was Princess Diana.

For all his historical sensitivity, Davies ends his book on a curiously scientific note. He presents us with a typology of “state death,” which he breaks down into five forms: implosion, conquest, merger, liquidation and “infant mortality.” The Soviet collapse is labeled an “implosion,” the “Velvet divorce” that split Czechoslovakia falls under liquidation, and brief spasms of rule like Kerensky’s constitutional Russia are Davies’s version of crib death. But this late capitulation to the categories of political science is belied by the immense amount of detail marshaled in Davies’s work. Unlike Jared Diamond, Daron Acemoglu and James Robinson—who privilege one cause (environment, economics, institutions) over all others—his instincts rebel against trading history for theory. Davies is that rare historian intent on measuring Cleopatra’s nose. Had it been shorter, you can be sure Vanished Kingdoms would have noted its precise dimensions.