Askold and Dir
The only foreign source to mention one of the co-rulers is the Arab historian Al-Masudi. According to him, "king al-Dir [Dayr] was the first among the kings of the "Saqaliba" (Slavs)." Although some scholars have tried to prove that "al-Dir" refers to a Slavic ruler and Dir's contemporary, this speculation is questionable and it is at least equally probable that "al-Dir" and Dir were the same person. It seems that in Old East Slavic it was originally "askold Dir" and not "Askold i Dir" as it is known from the Primary Chronicle. The word "askold" or "oskold" is derived from Old Norse "óskyldr" meaning "strange", so there was probably a ruler of Kiev called Dir by the Slavs and the Varangians called him something like "óskyldr Dyri"—"stranger Dir". The Rus' Varangians later forgot the meaning of "óskyldr" so Nestor wrote about two rulers of Kiev—about Askold and Dir.