In a 'mokkan' (a narrow strip of wood on which an official message is written: made after 'Taika no Kaishin' [Great Reformation of the Taika Era] till the introduction of the Ritsuryo system [a system of centralized government based on the ritsuryo code]) made in the period from Asuka-kyo place to Fujiwara-kyo palace, Omi Province was described as 'Chikatsu no umi' (近水海).
飛鳥京から藤原宮時代の木簡（大化の改新以後～律令制前）には近江国を「近水海」と記載されている。