The Dumnonii or Dumnones were a group of people who lived in an area called Dumnonia, which is now known as Cornwall and Devon, as well as parts of modern-day Dorset and Somerset. This region was located in the southwestern part of Britain. The Dumnonii lived there from at least the Iron Age until the early Saxon period. To the east of their land, the Durotriges tribe lived.

Etymology

William Camden, in his 1607 book Britannia, described Cornwall and Devon as parts of the same ancient region. He wrote that this area was once home to people called the Dunmonii by Solinus, the Damnonii by Ptolemy, or the Danmonii, as found in some older texts. Over time, this region was divided into two parts, now known as Cornwall and Devonshire. The part closer to the sea, once called the Danmonians’ land, is now called Devonshire by the English, Dewnan by the Cornish, and Duffneint by the Welsh, meaning "low valleys" because many people lived in valleys. The English name "Devonshire" comes from the Latin "Devonia," which was shortened over time.

Camden studied Welsh and may have been the first to connect the name "Dumnonii" to the idea of "deep valley dwellers" based on his knowledge of Welsh. The modern Welsh word for this region is Dyfnaint. Later, John Rhŷs suggested the name might come from a goddess named Domnu, meaning "the goddess of the deep." The root dubno-, found in names like Dumnorix and Dubnovellaunus, may mean "deep" or "earth." A similar group, the Fir Domnann of Connacht, had a similar name but no known connection.

The Roman name for Exeter, Isca Dumnoniorum, means "Water of the Dumnonii." The Latin name suggests the city was already a walled town near the River Exe before the Romans built their city around AD 50. The Dumnonii’s name became the basis for the English county of Devon and appears in Cornish (Dewnens) and Welsh (Dyfnaint). Amédée Thierry, a 19th-century historian, linked the Dumnonii to the Cornish people.

Victorian historians often called the group the Damnonii, a name also used for a different people in lowland Scotland. However, no connection between these two groups is known.

Language

The people of Dumnonia spoke a type of Celtic language called Southwestern Brythonic, which was similar to the earlier version of modern Cornish and Breton languages. Evidence of Irish immigrants, known as the Déisi, includes Ogham-inscribed stones they left behind. These findings are supported by studies of place names. Some stones are written in Latin, while others use both Ogham and Latin scripts. Tristram Risdon noted that a Brythonic dialect was still spoken in the South Hams area of Devon as late as the 14th century, in addition to its use in Cornwall.

Territory

In the 2nd century, Ptolemy’s Geography describes the Dumnonii as located to the west of the Durotriges. The name "Purocoronavium" found in the Ravenna Cosmography suggests the presence of a smaller group known as the Cornavii or Cornovii, possibly the ancestors of the Cornish people.

Gaius Iulius Solinus, likely writing in the 3rd century, noted: "This narrow strait separates the island of Silura from the land controlled by the Dumnonii, a British tribe. The people of this island still follow an old tradition: they do not use coins. Instead, they trade goods directly to meet their needs. They honor gods, and both men and women share knowledge of future events."

During the sub-Roman period, a Brythonic kingdom named Dumnonia formed, covering the entire peninsula. Some scholars believe this kingdom may have been made up of smaller, separate kingdoms.

A kingdom called Domnonée (alongside Cornouaille) was established in the Armorica region of France, across the English Channel from Britain. This kingdom appears to have connections to the British population, showing a long-standing link between people living along the western Atlantic coast. This connection is also supported by modern genetic studies of Devonian and Cornish populations.

Settlements

The Latin name for Exeter is Isca Dumnoniorum, which means "Water of the Dumnonii." This oppidum, or important town, was located on the banks of the River Exe and existed before the Roman city was built around AD 50. The word "Isca" comes from the Brythonic language, meaning "flowing water," which was the name given to the River Exe. The Gaelic word for water is "uisce" or "uisge." This is reflected in the Welsh name for Exeter: "Caerwysg," meaning "fortified settlement on the river Uisc."

Isca Dumnoniorum began as a settlement around the Roman fortress of the Legio II Augusta. It is one of the four poleis, or cities, listed by Ptolemy as belonging to the Dumnonii tribe. It is also mentioned in two routes from the late 2nd century Antonine Itinerary.

A legionary bath-house was built inside the fortress between 55 and 60 AD and was repaired soon after (around 60–65 AD). However, by around 66–68 AD, the legion moved to a new fortress at Gloucester. This led to the fortress at Isca being taken apart and abandoned. By around AD 75, work on the city's forum and basilica began on the site of the old fortress. By the late 2nd century, the city walls were completed. These walls were 3 meters thick and 6 meters high, enclosing the same area as the earlier fortress. However, by the late 4th century, the city was no longer thriving.

Next to the Durotriges, but farther west, were the Dumnoni. Their towns included: Voliba (14°45 52°00), Uxella (15°00 52°45), Tamara (15°00 52°15), and Isca, where Legio II Augusta was located (17°30 52°45).

In addition to Isca Dumnoniorum, Ptolemy’s 2nd century Geography lists three other towns. The Ravenna Cosmography includes the last two names (as "Tamaris" and "Uxelis") and adds more names that may represent other settlements in the area. These include:

Other Romano-British sites in Dumnonia include:

New settlements were built throughout the Roman period, such as those at Chysauster and Trevelgue Head. These sites had a style different from Roman designs. Near Padstow, an important site was inhabited from the late Bronze Age or early Iron Age until the mid-6th century. It is now buried under sand on the opposite side of the Camel estuary near St. Enodoc’s Church and may have been a coastal equivalent of a Saxon Shore Fort. Byzantine and African pottery has been found there. At Magor Farm in Illogan, near Camborne, an archaeological site has been identified as a villa.

Archaeology

The Dumnonii are believed to have lived in areas of Cornwall, Devon, Somerset, and possibly part of Dorset. Their cultural links, shown through their pottery, were with the Armorica region across the English Channel, not with the southeast of Britain. They did not have a central government: coins were uncommon, none made locally, and the design and location of Bronze Age and Iron Age hill forts, circular farms, and protected homes in the southwest suggest several smaller groups lived together.

Dumnonia is known for many settlements from the Romano-British era, but it does not have a system of villas. Local archaeology shows instead the isolated enclosed farms called "rounds." These farms remained after the Romans left Britain but were later replaced, around the 6th and 7th centuries, by open farms with names beginning with "tre" in the local language.

Like other Brythonic regions, Iron Age hill forts, such as Hembury Castle, were reinforced for use by leaders or kings. Important places like Tintagel were rebuilt during this time. Pottery from the Roman period has been found at many sites, and the sudden increase in Mediterranean and Byzantine pottery around 450 AD remains unexplained.

Industries

In addition to fishing and farming, the main source of income for the Dumnonii was tin mining. People mined in Dumnonia for a very long time, and tin was sent out from the ancient trading port of Ictis (St Michael's Mount). Tin was extracted, mainly using a method called streaming, as early as the 22nd century BC during the Bronze Age. West Cornwall, near Mount's Bay, was traditionally believed to have been visited by metal traders from the eastern Mediterranean.

During the first millennium BC, trade became more organized. First, the Phoenicians settled Gades (Cádiz) around 1100 BC, and later, the Greeks settled Massilia (Marseille) and Narbo (Narbonne) around 600 BC. Smelted tin from Cornwall was collected at Ictis, then sent across the Bay of Biscay to the mouth of the Loire River. From there, it traveled through the Loire and Rhone valleys to Gades. It was then shipped through the Mediterranean Sea to Gades.

Between about 500 and 450 BC, tin deposits became more important. Fortified settlements, such as Chun Castle and Kenidjack Castle, were built to protect tin smelters and miners.

The earliest written record about Cornish tin mining was written by Pytheas of Massilia in the late 4th century BC after he traveled around the British Isles. He described underground mining, though it is unclear when this practice began. Later writers, including Pliny the Elder and Diodorus Siculus, also noted Pytheas’s account.

It is likely that tin trade with the Mediterranean was later controlled by the Veneti. Britain was one of the places suggested as the Cassiterides, or Tin Islands. Tin mining continued during the Roman occupation, but production decreased when new tin sources were found in Iberia (Spain and Portugal). When these sources declined, tin production in Dumnonia increased and reached its highest level during the 3rd century AD.

Sub-Roman and post-Roman Dumnonia

The history of Dumnonia after the Roman Empire is very hard to understand because it mixes real events, legends, and confusing false stories. This information comes from many different sources written in Middle Welsh and Latin. Important sources for this time include Gildas's De Excidio Britanniae, Nennius's Historia Brittonum, the Annales Cambriae, the Anglo-Saxon Chronicle, William of Malmesbury's Gesta Regum Anglorum and De Antiquitate Glastoniensis Ecclesiae, the Black Book of Carmarthen, the Red Book of Hergest, Bede's Historia ecclesiastica gentis Anglorum, "The Descent of the Men of the North" (Bonedd Gwŷr y Gogledd) from Peniarth MS 45 and other places, and the Book of Baglan.