The year 1021 AD is the earliest date in which a European presence in the Americas can be scientifically proven, according to a new study.
Explorer Christopher Columbus has long been credited with being the first European to reach the Americas in 1492.
But historians say Nordic adventurers made it there before him nearly 500 years earlier.
Leif Erikson, an Icelandic explorer and the second of three sons of Erik the Red, is believed to be the first visitor to North America.
Now a study by a team of international researchers claims to have pinpointed the exact date to 1021.
The chopping of wood by Vikings at L’Anse aux Meadows - a site in Newfoundland, Canada which has been linked to Erikson - was dated to exactly the year 1021 AD, the researchers say in the new study, published in the Nature journal.
The three pieces of wood studied, from three different trees, all came from contexts archaeologically attributable to the Vikings, the study said.
Each piece of wood also displayed "clear evidence" of cutting and slicing by blades made of metal - tools not used by the indigenous population.
The exact year was determinable because a massive solar storm occurred in 992 AD that produced a distinct radiocarbon signal in tree rings from the following year.
Research director Associate Professor Michael Dee, of the University of Groningen in Holland, said: “The distinct uplift in radiocarbon production that occurred between 992 and 993 AD has been detected in tree-ring archives from all over the world.”
He said that each of the three wooden objects exhibited this signal 29 growth rings before the bark edge.
Study first author Dr Margot Kuitems, also of the University of Groningen, said: "Finding the signal from the solar storm 29 growth rings in from the bark allowed us to conclude that the cutting activity took place in the year 1021 AD.”
The researchers say that the number of Viking expeditions to the Americas, and the duration of their stay over the Atlantic, remain unknown.
All current data suggests that the whole endeavour was "somewhat short lived" - and the cultural and ecological legacy of the first European activity in the Americas is likely to have been small.
However, botanical evidence from L’Anse aux Meadows has confirmed that the Vikings did explore lands further south than Newfoundland.
Dr Kuitems said: “1021 AD is the earliest year in which European presence in the Americas can be scientifically proven.
“Previous dates for the Viking presence in the Americas have relied heavily on the Icelandic Sagas. However, these began as oral histories and were only written down centuries after the events they describe.
“Whilst contradictory and at times fantastical, the Sagas also suggest encounters occurred, both violent and amiable, between the Europeans and the indigenous people of the region.
“However, little archaeological evidence has been uncovered to support such exchanges."
She added: "Other medieval accounts also exist, which imply prominent figures on the European mainland were made aware the Vikings had made landfall across the Atlantic."
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies