In the Late Bronze Age, defended hilltop settlements along the northern shore of Morecambe Bay, with metalworking, special functions and long-term deposition of artefacts associated with them, were probably precursors to later Iron Age hill-forts. However, many of these defended settlements appear to have been abandoned, probably due to a deterioration in the climate from c. 1250 BCE to roughly the beginning of the Iron Age. The Iron Age in Britain saw the arrival of Celtic culture – including certain art forms and languages – as well as the obvious increase in the production of iron. The people of Great Britain and Ireland were divided into various tribes: In Cumbria the Carvetii may have dominated most of the county for a time, perhaps being based in the Solway Plain and centred on Carlisle, although an alternative view has their pre-Roman centre at Clifton Dykes. The Setantii were possibly situated in the south of the county, until both were perhaps incorporated into the Brigantes who occupied much of northern England. (The status – especially that of the relationship with the Brigantes – and location of the Carvetii and Setantii is disputed by historians). They probably spoke Cumbric, a variety of the ancient British language of Brythonic, (or Common Brittonic), the predecessor of modern Welsh, and probably named some of the county's topographical features such as its rivers (e.g. Kent, Eden, Cocker, Levens) and mountains (e.g. Blencathra). There appear to be many remains of Iron Age settlement in Cumbria, including hill forts such as those at Maiden Castle  and Dunmallard Hill and many hundreds of smaller settlements and field systems. However, securely dateable evidence of Iron Age activity in Cumbria is thin. In North Cumbria, hillforts have been dated to c. 500 BCE at Carrock Fell and Swarthy Hill, as well as a burial at Rise Hill and a bog body at Scaleby Moss. A large number of enclosure sites have been identified from aerial photographs in the Solway Plain. There are also possible sites re-used by the Romans at Bousted Hill and Fingland, as well as at Ewanrigg and Edderside. Early Iron Age finds in West Cumbria are limited to sites at Eskmeals and Seascale Moss (with another bog body). In the south, 'hillforts' have been identified at Skelmore Heads, Castle Head, Warton Crag and an enclosure at Urswick.