In 795, small bands of Vikings began plundering monastic settlements along the coast of Gaelic Ireland. The Annals of Ulster state that in 821 the Vikings plundered Howth and "carried off a great number of women into captivity". From 840 the Vikings began building fortified encampments, "longphorts", on the coast and overwintering in Ireland. The first were at Dublin and Linn Duachaill. Their attacks became bigger and reached further inland, striking larger monastic settlements such as Armagh, Clonmacnoise, Glendalough, Kells and Kildare, and also plundering the ancient tombs of Brú na Bóinne. Viking chief Thorgest is said to have raided the whole midlands of Ireland until he was killed by Máel Sechnaill I in 845.