There was no official document of history after the Engi era and it was very difficult to collect historical documents; in the following 1664, Gaho requested a roju Tadakiyo SAKAI to provide necessary assistance such as collecting ancient records.
日本には延喜年間以降の正史が無く史料収集など事業は難渋し、翌寛文4年、鵞峯は老中酒井忠清に古記録の収集など必要な援助を要請。