In this book, Snyder examines the political, cultural, and ideological context tied to a specific region of Central and Eastern Europe, where Joseph Stalin's Soviet Union and Adolf Hitler's Nazi Germany committed mass murders of an estimated 14 million noncombatants between 1933 and 1945, the majority outside the death camps of the Holocaust.

[1][7][12] The book highlights the similarities between the two regimes, with Snyder stating: "Hitler and Stalin thus shared a certain politics of tyranny: they brought about catastrophes, blamed the enemy of their choice, and then used the death of millions to make the case that their policies were necessary or desirable.

Snyder pointed out that "I am not counting soldiers who died on the fields of battle", saying that this "is not a complete reckoning of all the death that Soviet and German power brought to the region.

Snyder said that he "generally excludes from the count" deaths due to exertion, disease, or malnutrition in concentration camps; deportations, forced labor, evacuations; people who died of hunger as a result of wartime shortfalls, and civilians killed by bombings or other acts of war.

The geographic area covered by the "Bloodlands" is limited to Poland, Ukraine, Belarus, the Baltic states, and western Russian regions occupied by Germany.

[5] In assessing these reviews, Jacques Sémelin wrote: "While observers on the whole all join in paying tribute to Snyder's tour de force, they nevertheless don't hold back from subjecting him to several incisive criticisms.

"[4] Sémelin stated that several historians have criticized the chronological construction of events, the arbitrary geographical delimitation, Snyder's numbers on victims and violence, and a lack of focus on interactions between different actors.

"[5] Other positive reviews include those from Wendy Lower, who wrote that it was a "masterful synthesis",[25] John Connelly, who called it "morally informed scholarship of the highest calibre",[26] and Christopher Browning, who described it as "stunning",[5] while Dennis Showalter stated that "Snyder has written several first-rate books ... And Bloodlands takes his work to a new level.

"[27] Mark Roseman wrote that "the book's core achievement is ... to tell the story of Nazi and Soviet violence in a way that renders that savage chapter anew, and enduringly changes what we see.

"[31][32][33] In a summer 2011 article for the Slavic Review, Omer Bartov wrote that while Bloodlands presents an "admirable synthesis", it nonetheless "presents no new evidence and makes no new arguments", and stating that the book is "permeated by a consistent pro-Polish bias", eliding darker aspects of Polish–Jewish relations, and that Snyder's emphasis on German and Soviet occupation policies glosses over interethnic violence, commenting: "By equating partisans and occupiers, Soviet and Nazi occupation, Wehrmacht and Red Army criminality, and evading interethnic violence, Snyder drains the war of much of its moral content and inadvertently adopts the apologists' argument that where everyone is a criminal no one can be blamed.

For Gawronski, "Snyder walks a tightrope of deepening concern for the Jewish Holocaust and a most moving presentation while situating it within the suffering of other surrounding communities: I believe he accomplishes this very difficult task well.

"[35] Contemporary European History published a special forum on the book in May 2012, featuring reviews by Jörg Baberowski, Dan Diner, Thomas Kühne, and Mark Mazower as well as an introduction and response by Snyder.

The more provocative historians were in doing so and the more they thereby questioned the uniqueness, or the peculiarity, of the Holocaust, the more their work was met with resistance or even disgust, most prominently and controversially the German Ernst Nolte in the 1980s.

[38]Baberowski, a leading contemporary proponent of Nolte's views on the Holocaust, criticized Snyder for not going far enough to connect the genocide of European Jews to "the excesses of Stalin's dictatorship.

"[39] Diner expressed regret that Snyder did not discuss the legacy of Polish–Russian hostility and of the Polish–Soviet War, which would have given context for Soviet crimes in Katyn and Stalin's decision not to intervene during the Warsaw Uprising against the German occupier in 1944.

In the New Directions in the History of the Jews in the Polish Lands (2018), Dan Michman wrote: [F]rom the perspective of today, one can say that the pendulum has even moved so far in emphasizing Eastern Europe from June 1941 onward, and first and foremost its killing sites as the locus of the Shoah, that one will find recent studies which entirely marginalize or even disregard the importance to the Holocaust of such essential issues as the 1930s in Germany and Austria; the persecution and murder of Western and Southern European Jewry; first steps of persecution in Tunisia and Libya; and other aspects of the Holocaust such as the enormous spoliation and the cultural warfare aimed at exorcising the jüdische Geist.

Perhaps the bluntest example for this development is Timothy Snyder's book Bloodlands, which has been hailed on the one hand for its innovative perspective, but also extremely criticized by world-renowned experts on both Nazism and Stalin's Soviet Union.

"[40] In a September–October 2010 public debate in The Guardian,[41] Efraim Zuroff criticized what he described as the book's suggestion of a moral equivalence between Soviet mass murders and the Nazi Holocaust, and accused Snyder of providing a scholarly basis for the double genocide theory by emphasizing the Molotov–Ribbentrop Pact.

[13]Writing in the Financial Times in November 2010, Guy Walters stated that he found the book disturbing, commenting: "Some may find Snyder's staking-out of the area of the bloodlands too arbitrary for their tastes, and might accuse him of creating a questionable geographical delineation.

Writing for The New York Review of Books in November 2010, Anne Applebaum commented: Snyder's original contribution is to treat all of these episodes—the Ukrainian famine, the Holocaust, Stalin's mass executions, the planned starvation of Soviet POWs, postwar ethnic cleansing—as different facets of the same phenomenon.

His intention, rather, is to show that the two systems committed the same kinds of crimes at the same times and in the same places, that they aided and abetted one another, and above all that their interaction with one another led to more mass killing than either might have carried out alone.

Lazare also called attention to Snyder's suggestion that it was the Home Army's fear of communism that made it hesitant to help the Jewish Combat Organization, which also included communists, in the Warsaw Ghetto.