When did the Viking Age begin?

Spread of Christianity by c. 800 image: Utah State University

Historians have traditionally associated the starting point of the Viking Age with the raid on the Lindisfarne monastery in 793 AD. Located on the northeast coast of England, Lindisfarne was a centre of Christian learning and wealth. The sudden and violent raid by Norse seafarers was seen as marking the beginning of a series of similar incursions along the coastlines of Europe.
It was assumed that the Viking Expansion first occurred to the west, although this was almost certainly because annals produced by Christian monasteries in Frankia, England, Scotland, and Ireland, preserved written records of Viking attacks in these areas.
Annals (Latin: annāles, from annus, “year”) are a concise historical record in which events are arranged chronologically, year by year.

After the Council of Nicaea in 325, Easter tables were created using different methods for calculating Easter, extending years into the future. Monks in Ireland, Wales, and England began adding marginal notes about significant events to these tables in the 7th century. This practice evolved into compiling annals, primarily undertaken by monks, with the earliest known example being the Chronicle of Ireland.
However, in 2008 two ship burials in Salme, Estonia were discovered. The clinker-built ships appear to have been constructed AD 650–700, probably in Sweden, and they contained burials with Viking weapons – some fifty years before the apparent beginning of the Viking Age.

See: The Salme Ship Burials in Pre-Viking Estonia

In December 2015, the Swedish Research Council made one of the largest grants ever awarded to an archaeological project. Professor Neil Price of Uppsala University was awarded 50 million Swedish kronor (c. $6m USD) for a ten-year initiative entitled “The Viking Phenomenon”, establishing a new centre of excellence for the study of this crucial period in European history.
The project will run until 2025 and is intended to address several core questions:
Who really were the first Viking raiders, in a specific sense?
Why did they do what they do?
What kind of societies produced them, and why did they start to expand so violently into the world at precisely this time?