The Rus'–Byzantine Treaty of 911 is the most comprehensive and detailed treaty which was allegedly concluded between the Byzantine Empire and Kievan Rus' in the early 10th century. It was preceded by the preliminary treaty of 907. It is considered the earliest written source of Kievan Rus' law. The text of this treaty is only found in the Primary Chronicle (PVL), and its authenticity is therefore difficult to establish.
The text of the document is incorporated into the Primary Chronicle (PVL) sub anno 911. The text also includes speeches of the parties on the occasion.
Because the text of this treaty is only found in the Primary Chronicle (PVL), it is difficult to authenticate. Some scholars believe that the original text of the treaty was written in Medieval Greek, then translated into (Old) Church Slavonic, after which the Greek original was lost. Cross & Sherbowitz-Wetzor (1930) wrote about the earliest treaties in general:
Serhii Plokhy (2006) compared the surviving texts of the supposed Rusʹ–Byzantine treaties of 907, 911 and 944, noting that 'there is serious doubt that the dates attached to the texts of these treaties are reliable. Indeed, there is good reason to believe that the treaties are at least partly the result of later creative editing of original texts, either by the author of the Primary Chronicle or by his predecessors. For example, the text of the Rus' treaty of 911 with Byzantium, which is considered more reliable than the other two, does not include a list of Rus' towns', unlike those of 907 and 944.
The text has many affinities in content and phrasing with the trade treaties later concluded by Byzantium with the merchant republics of Italy. No treaties of comparable complexity and antiquity are known among the other societies in Europe of that time.
It was composed in two languages and signed personally by Emperor Leo VI the Wise.
All the names of the Rus' envoys mentioned in the treaty appear to be Scandinavian (attested or reconstructed Old Norse forms in parentheses): Farlof (Farulfr), Ver/lemud (Vermu(n)dr), Rulav (Rollabʀ), Fost (*Fastuʀ), Frelavc (Frilleifr), Inegeld (Ingjaldr), Karly (Karli), Karn (Karna, attested in a Swedish runic inscription), Lidul(f) (Lidulif < Leiðulfr, but litulf is attested from a runic inscription), Ruald (Hróaldr), Rjuar (Hróarr), Truan (Þróndr or Þrandr). Cross & Sherbowitz-Wetzor (1930) observed: 'In the portion of the account of Oleg's expedition which is of native Russian [sic] origin the Russes and the Slavs are clearly distinguished, but in the treaty text itself the whole expedition is designated as Rus'.'
Apart from the chronology at the start of the PVL (18:10–12), the Treaty of 911 is the only place in the PVL where Oleg is referred to as a кънязя k"nyazya "prince". If this is accurate, then Oleg would have to have been a prince in his own right (suo jure). On the other hand, Oleg reportedly told Askold and Dir that he was роду къняжа rodu k"nyaza "of princely stock/lineage" (PVL 23:14–16), instead of a prince himself, when he is said to have killed them and taken over Kiev in 881/2. At Rurik's death, the PVL only calls Oleg his "kinsman", given the care of Rurik's son Igor, and acting as a regent on Igor's behalf, rather than being a prince in his own right.
. The Origins of the Slavic Nations: Premodern Identities in Russia, Ukraine, and Belarus . Serhii Plokhy . 2006 . Cambridge University Press . New York . 978-0-521-86403-9 . 10–15 . 27 April 2010.