The files on the Office in Charge of Foreign Affairs (Zongli yamen) kept in the archive of the Institute of Modern History cover the period from 1861 to 1901. Certain files either pre-date or post-date this period. For example, there are diplomatic files compiled at a time before the office was created, such as the details of preparation for the foreign office and their supplements and the New File on Four Nations, etc. The other reason is because during the archiving process some files belonging to the same categories, but different foreign offices were not separated out. This decision was made for the sake of reading consistency. These files are in “original file” and “copy file” formats. The files are divided into forty-one series, according to subject matter and include dispatches from ambassadors and the installation of consulates, trade and tariffs, religious affairs, Korean files, and Chinese laborers, etc.