Answer:
The Vikings deemed it no longer fit and beneficial to raid due to the change in time. Moreover, the Norwegian king Harald Fairhair had passed.
Explanation:
http://www.hurstwic.org/history/articles/society/text/what_happened.htm#:~:text=At%20the%20Battle%20of%20Stamford,profitable%20or%20desirable%20to%20raid.
