One common, simplifying assumption in open economy macroliterature is that the rest of the world can be thought of as a representative economy. This article formally investigates conditions under which this assumption can be justified using a multicountry general equilibrium model as a laboratory. We derive the conditions that ensure the existence of the equilibrium and study the properties of the equilibrium using large N asymptotics. Thereby, we show that the two‐country framework is a valid approximation only for economies that have diversified trade linkages and only when there is no globally dominant economy among the foreign economies.