And also, how much effect on their world did the Norsemen have?
This is a very difficult thing to pin down historically because these events occurred before written historical records. Here's some previous posts related to the topic that might help shed some light on the issue:
https://www.reddit.com/r/AskHistorians/comments/2tkg1b/who_were_the_rus_and_what_happened_to_them/