http://news.discovery.com/history/us-history/vikings-native-american-woman.htm

"It was thought at first that (the DNA) came from recently established Asian families in Iceland," CSIC researcher Carles Lalueza-Fox was quoted as saying in a statement by the institute. "But when family genealogy was studied, it was discovered that the four families were descended from ancestors who lived between 1710 and 1740 from the same region of southern Iceland."

The lineage found, named C1e, is also mitochondrial, which means that the genes were introduced into Iceland by a woman.

"As the island was virtually isolated from the 10th century, the most likely hypothesis is that these genes corresponded to an Amerindian woman who was brought from America by the Vikings around the year 1000," said Lalueza-Fox.