Historical International Relations is a multidisciplinary sub-field of International Relations, concerned with the historical dimensions of states, state-systems and all things international. 

As a quarry for data, testing-ground for theory and site of investigation, history has always been one of the unacknowledged partners of the academic discipline of International Relations. Over the last decades, historical scholarship has emerged in its own right in the discipline. This sub-field is closely aligned also with history and historical sociology but puts the emphasis squarely on the historical dimension of international relations.