Hogbacks take the form of recumbent monuments, generally with a curved ('hogbacked') ridge, often also with outwardly curved sides. This shape, and the fact that they are frequently decorated with 'shingles' on either side of the central ridge, show that they are stylised 'houses' for the dead. The 'house' is a Scandinavian type, and hogbacks are agreed to have originated among the Danish settlers who occupied northern England in the 870s after the fall of the Anglo-Saxon kingdom of Northumbria. It has been suggested that the monument-type was invented about 920. There are particular concentrations of hogbacks in Yorkshire and Cumbria, the former being their likely area of origin. Individual examples are found over a much wider area, however, from Derbyshire to Central Scotland. There are stray examples as far afield as the Northern Isles, Orkney and Cornwall.Ireland has a single example at Castledermot, Co. Kildare. The most numerous collections are the ones preserved in St Thomas's church of Brompton, Yorkshire. Discovered in 1867 following the restoration of the church, six were taken to Durham Cathedral Library leaving four whole ones and fragments of others at Brompton. They are characterized by carvings of bears hugging the slabs with strapwork in their mouths. Elsewhere five are in the parish kirk of Govan, once a rural parish, but now part of Glasgow. There is a fine example in the visitor centre on Inchcolm island in the Firth of Forth.