Humans have lived in Shetland since the Mesolithic period. The earliest written references to the islands date back to Roman times. The early historic period was dominated by Scandinavian influences, especially from Norway, and the islands did not become part of Scotland until the 15th century. When Scotland became part of the Kingdom of Great Britain in 1707, trade with northern Europe decreased. Fishing has continued to be an important aspect of the economy up to the present day. The discovery of North Sea oil in the 1970s significantly boosted Shetland’s economy, employment and public sector revenues.
(Taken from Wikipedia)