In ancient China, there were gods of alcohol named Yi Ti and Du Kang (pronounced as toko in Japanese), and this opinion insists that the term came from the story that people who made good sake were given a surname (written as 氏 in Japanese) Toko (written as 杜康 in Japanese) which was derived from the latter god.
古代中国では儀狄（ぎてき）と杜康（とこう）という酒の神がいたが、後者に由来して良い酒を造った者に杜康という氏を授けたことに由来するとする説である。