The oldest reference to an example of Tomokuyu was in "Shinsen Shojiroku" (Newly Compiled Register of Clan Names and Titles of Nobility) composed in the Heian period, saying "Tajibe (people who are privately owned by the Emperor and in charge of education for the Prince) was set in various districts to be Prince's Tomokuyu."
湯沐邑の用例として最も古い時代を参照するものとしては、平安時代に作られた『新撰姓氏録』に、「諸国に多治部を定めて皇子の湯沐邑にした」とある。