Résumé
We build a theoretical framework consistent with historical evidence in which empire-building is explained by price and predatory competitions on the market for protection. We explore how the assets structure possessed by the buyers of protection influences the nature of protection and in fine the size of empires. Our main contribution is to introduce a distinction between two types of rent, namely an “absolute” and a “differential” one. The first corresponds to rents extracted by empires using threats and coercion; the second, to economic advantages conferred on subjects of an empire.