Ringfort

Ringforts or ring forts are small circular fortified settlements built during the Bronze Age, Iron Age and early Middle Ages up to about the year 1000 AD. They are found in Northern Europe, especially in Ireland. There are also many in South Wales and in Cornwall, where they are called rounds. Ringforts come in many sizes and may be made of stone or earth. Earthen ringforts would have been marked by a circular rampart (a bank and ditch), often with a stakewall. Both stone and earthen ringforts would generally have had at least one building inside.

In Irish language sources they are known by a number of names: ráth (anglicised rath, also Welsh rath), lios (anglicised lis; cognate with Cornish lis), caiseal (anglicised cashel), cathair (anglicised caher or cahir; cognate with Welsh caer, Cornish and Breton ker) and dún (anglicised dun or doon; cognate with Welsh and Cornish din). The ráth and lios was an earthen ringfort; the ráth being the enclosing bank and the lios being the open space within. The caiseal and cathair was a stone ringfort. The term dún was usually used for any stronghold of importance, which may or may not be ring-shaped.

In Ireland, over 40,000 sites have been identified as ringforts and it is thought that at least 50,000 ringforts existed on the island. They are common throughout the country, with a mean density of just over one ringfort within any area of 2 km² (0.8 sq mi). It is likely that many have been destroyed by farming and urbanisation. Mapping in County Cork and Waterford in 1773 showed 73 "earthworks" with only 20 recorded in 1937. However, many hitherto unknown ringforts have been found thanks to early Ordnance Survey maps, aerial photography, and the archaeological work that has accompanied road-building.

In Cornwall, parts of Devon, and south Wales, enclosed settlements share many characteristics with the Irish counterparts, including the circular shape and souterrains (fogous), and their continuing occupation from the Iron Age into the early medieval period; the form later influencing the distinctive circular shell-keeps found across the medieval Severnside region. Few Cornish examples have been archaeologically excavated, with the exception of Trethurgy Rounds.

Hillforts are also known from Scandinavia, of which nineteen can be found on the Swedish island of Öland alone.

These hillforts are not to be confused with Viking ring fortresses, of which seven are known from Denmark and southern Sweden, all from around 980 in the Viking Age. The Viking forts all share a strikingly similar design and are collectively referred to as Trelleborgs, after the first excavated fortress of that type in 1936. All the Viking ring fortresses are believed to have been built within a very short timeframe, during the reign of Harald Bluetooth, but for yet unknown military purposes. They might have served as boot camps for Sweyn Forkbeard's men before his invasion of England in 1013.

The debate on chronology is primarily a result of the huge number of ringforts and the failure of any other form of settlement site to survive to modern times in any great quantity from the period before the Early Christian period or from Gaelic Ireland after the Anglo-Norman arrival. Three general theories mark the debate on the chronology of Irish ringforts; firstly the theory that wishes to date ringforts back into the Iron Age period; secondly, the theory that seeks to see the continuation of ringfort habitation into the later medieval and even the Modern Period; finally, the more common and generally accepted theory that ringforts were a product of the second half of the first millennium (543-991), a theory which has been given greater definition by Matthew Stout in recent years. According to the authoritative New History of Ireland (2005), "archaeologists are agreed that the vast bulk of them are the farm enclosures of the well-to-do of early medieval Ireland".

The theories that the ringfort either pre- or post-dates the Early Middle Ages in Ireland, are both based on essentially the same premise, as is highlighted here by Tadhg O'Keefe in relation to the latter argument: