“Viking history” is pretty late. While Norse culture is much older, the (written) history about it only started when christian or muslim scholars started to write it down. And they only did that once the vikings started raiding and trading with the christian and muslim world at around 800 CE. They established trade networks and colonies along the big rivers of eastern Europe and reached the black sea and Caspian sea, which is most likely the origin of the ring the post is about.

Islam was founded 600 CE so yes, you are right.