This group of deities was known in Luwian as DINGIRMEŠ Marwāinzi (𒀭𒈨𒌍𒈥𒉿𒀀𒅔𒍣)[1] and ᴰMarwayanza (𒀭𒈥𒉿𒅀𒀭𒍝), and in Hittite as ᴰMarkuwayaš (𒀭𒈥𒆪𒉿𒅀𒀸), all meaning lit.
[7] Despite their foreign origin, the Dark Gods and Iyarri had cult places primarily in Central Anatolia and the regions inhabited by Luwians, and Iyarri appeared in Anatolian theophoric names, thus attesting that the people who gave these names saw these deities as being part of their own culture, thus showing that they had become firmly rooted in the Hittite and Luwian religions and had not been transmitted to the Anatolian peoples through the intermediary of Hurrian religion.
[2] The Heptad was also present in the religion of the Hurrian populations of Kizzuwatna:[9] The name "the Dark Ones" not only assigned an awe-inspiring appearance to this group of deities, but also ascribed to them a negative role.
[4] As suggested by their collective name, the Dark Gods were considered to have a malevolent nature,[2] which is also attested through their function in the Uḫḫamuwa ritual from Arzawa, where they represented pernicious forces.
[12] A Heptad of Tarḫunna (𒊭𒀭𒌋𒀭𒐌𒐌𒁉) also appears in a list structured like a kaluti- of the Hurrian tradition of Kizzuwatna, which itself describes a late ritual connected to the Hattian myth of the Moon falling from Heaven out of fear of the thunder, lightning and rains of the storm-god.