In stark contrast, George Vernadsky believed that the khagan had his headquarters in the eastern part of the Crimea or in the Taman Peninsula and that the island described by Ibn Rustah was most likely situated in the estuary of the Kuban River.
Constantine Zuckerman k temu dodaja, da je Ibn Rustah uporabil tekst neznanega avtorja iz okoli leta 870 in poskušal natančno prenesti naslove vseh vladarjev, ki jih je opisal njihov avtor, zato so Ibn Rustahovi zapisi še bolj dragoceni.