A graduate of the École Normale Supérieure, Thomas holds a PhD in history from the École des Hautes Études en Sciences Sociales. He is currently assistant professor at the Collège de France and editor at La Vie des Idées. His research looks at Native American reservations as colonial societies, and addresses the politicization of indigenous communities in the 20th century. His PhD, in particular, examined the role of military service among Native American veterans of World War One.