In fact, many mokkan were discovered from excavation research of the Fujiwara-kyo (the Fujiwara Palace; the ancient capital of Fujiwara) and Heijo-kyo, and the statements on those mokkan indicated the commodities were mostly paid to the capital as a tax.
実際、藤原京・平城京の発掘調査から多数の木簡が出土しており、これら木簡のほとんどは都に税として納められた物品を示す記述であった。