Monumental ship burial beneath ancient Norwegian mound predates the Viking Age

It isn't like boats were invented in Scandinavia by the vikings. At Tanum, close to the present Norwegian border we have rock carvings dating back to 1700BCE, with prominent ships depicted. Boatrs have been important in Scandinavia for a long time.

https://www.tanumworldheritage.se/rock-carving-facts/?lang=e...

Is my understanding of carbon dating needing an update or the precision to distinguish 100y difference on a 1.2k to 1.3k years base not enough?

If 100y is the difference it could just be that the tree grew for 100y and the at the end they used it?