The results are interesting but the article muddles the issue by confusing terminology. At the time, "Viking" did not denote certain people or ethnic groups, i

The results are interesting but the article muddles the issue by confusing terminology. At the time, "Viking" did not denote certain people or ethnic groups, it denoted an activity - traveling (and raiding) by boat. So a person might be described as "in viking" for the summer. Only later have the people who did this activity been called "vikings". So nobody "self identified" as viking at the time. The article muddles this by talking about "ethnic vikings" whatever that means, and "viking ancestry". Probably "Scandinavian" is meant. But the article at one hand talks about "Viking DNA" and at the same time claims vikings are not an ethnic group. Edit: This criticism applies to the article, not the underlying paper which seem to be much more careful with terminology. It defines a "viking culture" existing outside of Scandinavia (e.g. in Scotland) with Scandinavian cultural links but where members of this culture were not necessarily of Scandinavian descent. It also examines remains of an ill-fated raiding party in Estonia which were Swedish vikings in the traditional definition. And then it examines DNA from viking-age burial sites inside Scandinavia.