Riving, a Viking-age woodworking technique
This is an interesting article, but riving is not specifically Viking. It was the primary method of producing workable wood blanks from tree trunks in every civilization that used wood blanks. Which is to say, it was used all over Europe and Asia (at least), for at least the last 2000-plus years. I'm not as familiar with the woodworking traditions of Africa or pre-European-contact North or South America, so I don't know whether they used wood blanks.It's also used today by "green woodworkers" - woodworkers who specialize in building using non-dried wood. This mostly includes chair makers, but also some others. You can buy riving tools from a lot of places. Lie-Nielsen makes a very nice riving froe. You can also find antique ones at almost any antique woodworking tool show.