When was Iceland believed to be first inhabited?

The general consensus is the second half of the 9th century was when the first settlers came to Iceland. According to Ari Thorgilsson, a 12th century Icelandic chronicler, 870 and 874 are used as dates for the first settlement. But later historians question the reliability of the dates. Archeological evidence points to a settlement date in the 9th century.

The Icelandic Age of Settlement traditionally spans between 874 to 930, the last date was when the Icelandic Commonwealth was established and most of the island's usable land had been claimed by settlers.

Earlier evidence of occupation has been found. There is some evidence of a monastic settlement from the British Isles in a cave in southern Iceland that dates to around 800. And remains of a dwelling that was dated to have been abandoned between 770 and 880, putting the range a bit earlier than the traditional dates, but no evidence of it being a year-round permanent settlement.

The reasons for settling in Iceland are varied. Pressure of a growing population in Scandinavia with not enough arable land, and civil strife in Norway are two prominent reasons mentioned. Iceland was uninhabited and unlike the British Isles, land could be obtained without displacing any earlier settlers.