So how far did they get? To Contantinople...
History here includes this factoid:
The first record of Vikings in Byzantium is in 839 when a delegation had to return home via Germany. A more forceful encounter occurred in 860 when a large raiding force terrorized Constantinople for ten days. Trading treaties were made in 907 and 911.
An interesting element of these treaties is that they gave the Rus unlimited free baths.