 Georgy Vernadsky even identified the Oleg of the Schechter Letter with Igor 's otherwise anonymous eldest son , whose widow Predslava is mentioned in the Russo @-@ Byzantine treaty of 944 . Alternatively , V. Ya . <unk> speculated that Helgu @-@ Oleg of the 940s was one of the vernacular princes of Chernigov , whose ruling dynasty maintained especially close contacts with Khazaria , as the findings at the Black Grave , a large royal kurgan excavated near Chernigov , seem to testify . However , the academic mainstream has not endorsed either of these theories . 
