The National Book Award-winning historian of Stamped from the Beginning charts how “great replacement theory” has moved from the margins to become the most dominant political theory of our time—and what we can do to safeguard democracy from this insidious threat.

Recall the words chanted in Charlottesville, Virginia, but heard around the world: “You will not replace us!” Recall the string of mass shooters around the world—in Oslo and Christchurch, Buffalo, El Paso, and Pittsburgh—who claimed their crimes were a defense against “White genocide.” Recall business and media figures cultivating anxiety and furor over demographic change. These incidents only scratch the surface of this ascendant idea: Popular and ruling politicians in every region of the world have been expressing some version of great replacement theory, eroding democratic norms in the name of preventing demographic change and restoring national greatness.

What is great replacement theory? Variations on the theory have existed for centuries, but it was given this name by a French novelist in 2011 who believed Black and Brown immigrants were “invading” Europe, brought by shadowy elites to “replace” Europe’s White population. From there, politicians and theorists—whether in the United States or the United Kingdom, Germany or Chile, Hungary or Australia—repackaged the conspiracy as a story of “globalists” welcoming “migrant criminals” and diversity initiatives to take away the jobs, cultures, electoral power, and the very lives of White people. Over time, great replacement theory has expanded the threat to include citizens, men, Jews, Christians, heterosexuals, and ethnic majorities in countries as distinct as Russia, El Salvador, Brazil, Italy, and India. All are targeted with the message that they are under an existential attack that only a strongman can prevent.

In our fast-shifting political landscape, most people are unfamiliar with this theory’s origins and its spread, which isn’t a coincidence. In Chain of Ideas, international bestselling author Ibram X. Kendi uses exacting and clear prose to uncover the roots of great replacement theory and its various mutations around the world. It is an unsettling but indispensable global history of how great replacement theory brought humanity into this authoritarian age—and how we can free ourselves from it.