Concerning the characteristics of the documents related to the Takeda clan, it is pointed out that while many documents written during the Shingen/Katsuyori era, the era after the Takeda clan established its wide territory, are existing, the number of those written during Nobutora era or before is quite small.
武田氏関係文書の特徴として、文書の多くは戦国期に武田氏の拡大領国が確立した信玄・勝頼期に集中し、信虎期以前のものが極端に少ないことが指摘されている。