The Hebrides were settled early on in the settlement of the British Isles, perhaps as early as the Mesolithic era, around 8500-8250 BC, after the climatic conditions improved enough to sustain human settlement. There are examples of structures possibly dating from up to 3000 BC, the finest example being the standing stones at Callanish, but some archaeologists date the site as Bronze Age. Little is known of the people who settled in the Hebrides but they were likely of the same Celtic stock that had settled in the rest of Scotland. Settlements at Northton, Harris, have both Beaker & Neolithic dwelling houses, the oldest in the Western Isles, attesting to the settlement.
The earliest written mention of the Outer Hebrides was by the Greek historian Diodorus Siculus in 55 BC. He wrote that there was an island called Hyperborea (which means "Far to the North") where a round temple stood from which the moon appeared only a little distance above the earth every 19 years, an apparent reference to the stone circle at Callanish. Pomponius Mela, a Roman-Spanish writer of the first century, refers to a group of seven islands which he gave the name Haemodae. Other ancient writers such as Pliny the Elder, the Egyptian astronomer Ptolemy, and Solinus (3rd Century AD) all seem to mention the Hebrides, attesting to some contact of the peoples there to the Roman world. Little is known of the history of the peoples of the Hebrides before the 6th century as they, like the rest of Scotland, were in the depths of what centuries later became known as the Dark Ages. The first written records of the islands comes with the arrival of St. Columba in the 6th century AD. It was this Irish-Scottish saint who first brought Christianity to the islands in the 6th century, founding several churches.