Oyama insists that Dogo yuokahimeibun was forged during the Kamakura period because it first appeared as quotations in the "Manyoshu Chushaku" (Annotated Manyoshu) written during the Bunei era (1264 - 1275) by Sengaku and the "Shaku Nihongi" (Annotated Nihonshoki) written between 1274 and 1301 (Iyo no Kuni Fudoki Itsubun).
大山説では道後湯岡碑銘文は仙覚『万葉集註釈』（文永年間(1264年～1275年）頃）と『釈日本紀』（文永11年～正安3年頃（1274年～1301年頃））の引用（伊予国風土記逸文）が初出であるとして、鎌倉時代に捏造されたものとする。