Conflict can turn into genocide but not all conflicts have a genocidal outcome. At the theoretical level, Kiernan identifies four necessary ingredients in the making of a genocidal situation: the existence of political regimes that embrace cults of antiquity, an existing ethnic enmity, the presence of expansionist polities, and the pervasive influence of agrarian ideologies. A crucial preoccupation with restoring purity and order follows from all these four prerequisites: concerns about modernity often find expression in celebrations of ancient eras; spatial proximity can fuel ethnic enmity and lead to the envisioning ‘purified’ spaces; an expansionist polity is likely to encompass ethnic diversity; and an agrarian ideology is liable to propose an agricultural solution (that means, extirpation) to what is perceived as intolerable disorder. Blend these four ingredients together in different configurations and you are likely to encounter an explosive circumstance.

Not only does 'Blood and Soil' identify the ingredients; it also recognises the crucial processes that underpin their combination into an explosive mixture. Genocidal phenomena, Kiernan argues insightfully, are actually inherently contradictory occurrences where an anxious perception of a specific trend, or a series of developments, produces sustained counterpoint imaginings. Reality is going, or seems to be going one way, while the imagination proceeds in the opposite direction. It is out of this tension that a genocidal impulse is born: "Over the centuries, these strange social landscapes – hills of technological progress cut by ravines of ideological reaction – are littered with apparently contradictory signposts that nevertheless help trace the historical path to genocide. For example, slaveholding landlords idealize the sturdy, independent peasant. An efficient new agricultural economy fertilizes the pastoral imagination. The fetish for cultivation produces a romanticization of pristine forest. Urban growth fosters a desire to return to the countryside." (pp. 26-27)

Kiernan is right: all the atrocities he deals with in his narrative – and he deals with quite a few – display all these elements together with a pattern of disturbed perception that can transform anxiety and paranoia into genocidal action. Yet again, in one way or another all political entities display all these foundational traits at all times. Political power routinely needs to refer to legitimating moments located in the past; an ethnic self can only exist through reference to a number of definitory alterities; polities intensify their sovereign prerogatives and extend them if they are not busy preventing others from subverting them or expanding theirs; and rarely a reliable supply of foodstuff is guaranteed by hunting and gathering practices alone. According to Kiernan’s approach, the original question of this book (that means, ‘what are the fundamentals of genocide’) could thus be reversed: ‘what is it that prevents normal situations – and the four ingredients identified here are quite standard – from precipitating into genocidal rage’? After Kiernan’s impressive and unprecedented compilation of atrocities, we know better, but we don’t know for sure. In the end, even if Blood and Soil describes genocide through history (and in doing so does something that has not been done before), it not yet explains it.

Moreover, even if Kiernan dedicates an entire section (out of three) to settler colonialism, references to settler colonial phenomena disappear at the beginning of the “Twentieth-Century Genocides” third section. This choice is quite natural; after all, Blood and Soil is organised chronologically, not thematically. But the link between settler colonialism and genocide is thus advanced and not systematically tested. How about twentieth century instances of genocidal activity linked to the settler colonial imaginings and realities, from Libya, to Palestine, Algeria, Kenya? One result of this periodisation is that the genocide of Herero and Nama in German South West Africa, for example, is thus positioned more as a coda to a nineteenth century history than a precursor to a twentieth century one.

There is a long lasting interpretative tradition that identifies a structuring link between settler colonialism and genocide, a tradition that includes Francis Bacon, who preferred “a Plantation in a Pure Soile” (that is, uninhabited locales) and knew the difference between “Extirpation” and “Plantation”, Max Weber, who noted that “conquering peasant communities” have consistently sought to wipe out native populations, and Raphael Lemkin himself, the originator of genocide as a legal category. Settler colonial circumstances more immediately than any other display the four fundamental ingredients of genocide emphasised in Blood and Soil: settler colonialism is premised on a ‘return’ (to the land, to an ancient way of life, to the possibility of enjoying ancient freedoms, and so on), unavoidably and automatically establishes an ethnic enmity, is inevitably constituted through an expansionist move, and is one expression of a cohesive agrarian ideology. So: are settler colonial phenomena inherently genocidal? Again, even if we do know better, we do not even know how the author would answer.

Another example of an unresolved ambiguity is represented by Kiernan’s extended reconstruction of Thomas Jefferson shifting dispositions towards the indigenous people that occupied the area earmarked for US expansion. "Over time, Jefferson’s projects for Indians ranged widely, from peaceable assimilation with white American farmers to what we would now call ethnic ‘cleansing’ of the Indians, first in wartime, then in peace, and extending to extermination if he deemed necessary. In his mind all these options involved the disappearance of Indian communities." (p. 327)

And yet Kiernan also concludes that “Jefferson did not advocate extermination of Indians because they were Indians” (p. 320). A deferential approach in dealing with this founding father contradicts the very evidence that the book produces in abundance. True, Jefferson may have conceived of “peaceable assimilation” as one of the strategies accessible to an expanding settler polity, but this flexibility and the continued availability of a theoretical possibility for eventual assimilation changes very little in the context of a comprehensive, systematic, sustained, unambiguously articulated, violent and ultimately effective project of ethnic eradication. The fact that mass murder was selectively performed on the frontier should not distract; unrestrained violence and its threat systematically support each other: one is released to institute an exemplary precedent and make its threat more plausible, the other is recurrently threatened to justify its delivery.

On the other hand, even if the interpretative framework is cast somewhat inconsistently and, at times, ineffectively, and even if quite a few remarkable atrocities have been omitted, the reading, as supported by the information presented and its richness remains compelling. (A reference to what is left out is rather unfair: Kiernan does cover more than anyone else has, and yet the centuries that precede the modern era are actually packed with genocidal instances both inside and outside Europe – from the serial resettlement of populations and their consequences to the Crusades, and the wars of religion that characterise the sixteenth and seventeenth centuries are actually crammed with genocidal outbursts.) This book ultimately provides a reliable compilation of genocidal phenomena, their chronology and genealogy, and Kiernan endeavours effectively to impose a remarkable structuring coherence on an impressive amount of data. At the same time, he convincingly emphasises discursive links and resonances between different epochs and locations. You try and write a book like this.