become Wessex was traversed by the Harrow Way, which can still be traced from Marazion in Cornwall to the coast of the English Channel near Dover, and was probably connected with the ancient tin trade. In the Late Neolithic, the ceremonial sites of Avebury and Stonehenge were completed on Salisbury Plain, but the final phase of Stonehenge was erected by the so-called "Wessex culture" of the Middle Bronze Age (). The area has many other earthworks and erected stone monuments from the Neolithic and Early Bronze periods, including the Dorset Cursus, an earthwork long and wide, which was oriented to the midwinter sunset. Although agriculture and hunting were pursued during this long period, there is little archaeological evidence of human settlements. By the Iron Age, Celtic British tribes such as the Durotriges, Atrebates, Belgae and Dobunni occupied the future Wessex. Following the Roman conquest, from the 1st century AD, numerous country villas with attached farms were established across Wessex, along with the important towns of Dorchester and Winchester (the ending -chester comes from Latin castra, "a military camp"). The Romans, or rather the Romano-British, built another major road that integrated Wessex, running eastwards from Exeter through Dorchester to Winchester and Silchester and on to London. In the mid-4th century there were increasing raids on Roman Britain by peoples such as the Picti, Scotti, Attacotti and Franks, as well as the Saxons. In 367, these tribes simultaneously invaded Britain from the north, west and east. The invaders reportedly defeated or co-opted Roman forces in most parts of northern and western Britain. However, the Roman general Theodosius had recaptured most areas by the end of 368. In 380–1, Magnus Maximus defeated further raids. However, there was increasing internal conflict across the Roman Empire. During 383–4, in the context of the overthrow of Emperor Gratian, Maximus took most of the garrison from Britain to Gaul, where he was made Augustus of the West, ruling Britain, Gaul, Spain and Roman Africa. Following the death of Maximus in 388, Roman authority in Britain again declined. During the late 390s, Stilicho attempted to restore control, with a campaign against the Picti, but this was undermined in 401 when Stilicho transferred troops to the Continent to fight the Goths. Two subsequent Roman rulers of Britain were murdered. In 407, a Roman officer in Britain, Constantine III declared himself Augustus of the West, and left for Gaul, taking