The three most frequently commented texts of the classical literary canon are Kokin wakashu or KKS, Ise monogatari or The Tales of Ise, and Genji monogatari or The Tale of Genji. Imperial waka anthologies for the three centuries after KKS were ignored by commentators until the eighteenth century; the same is true for The Tale of Sagoromo, a narrative fiction the waka of which were considered comparable to those of Genji in late Heian and Kamakura times. One factor must be that KKS and Tales of Ise themselves incorporate distinctive forms of commentary. KKS can be defined in fact as a corpus of cited poems framed by two kinds of editorial comments and two "prefaces". The earliest extant commentaries on The Tales of Ise inclined toward extravagant allegoresis incorporating strains of Esoteric and Tantric Buddhism and Shinto that flourished in the thirteenth and fourteenth centuries, often intertwined with heterodox KKS commentaries of a similar bent.