The finds were made by teams working on the £17 million A75 Dunragit bypass in Wigtownshire.
Tools, arrowheads, urns and bead necklaces from the Mesolithic (9000 BC to 4500 BC), Neolithic (4500 BC to 2000 BC), Bronze (2500 BC to 800 BC) and Iron Ages (800 BC to 500 AD) were found, along with the Iron Age village and a Bronze Age cemetery.
A 130-piece jet bead necklace was of particular interest to archaeologists, who were able to trace its origin in Whitby, North Yorkshire, around 155 miles from where it was found.
The discoveries were showcased as work on the new road was completed, and they have been described as "exciting" by Historic Scotland.
Scottish Transport Minister Keith Brown viewed the artefacts in Edinburgh today, and said: "The finds at Dunragit, which would have remained uncovered had the new bypass not been built, are truly stunning, and underline the importance of the value we place on meeting our environmental obligations as we plan and construct essential new infrastructure.
"These are really exciting discoveries and tell us so much about our history in south-west Scotland. The concentration of artefacts from the Mesolithic to post-medieval periods was highly unexpected, but gives an invaluable insight into the land use and settlement of south-west Scotland over the past 9,000 years.
"The necklaces are of particular interest because they are the first such necklaces to be uncovered in the south west of Scotland."
Further examinations are being carried out on the finds to help conserve them and a decision is still to be made on where the various collections will be stored or put on display.
Rod McCullagh, senior archaeology manager at Historic Scotland, said: "The new bypass has been constructed while successfully avoiding the known archaeology, and an unforeseen wealth of archaeological information has been recovered.
"The team of archaeologists from Amey and Guard Archaeology Ltd have uncovered the remains of dwellings and burials spanning over 7,000 years of prehistory.
"In addition, numerous smaller sites have been discovered which seem to relate to the use and exploitation of the land both through hunting and farming.
"These are exciting discoveries which offer a much richer understanding of the settlement of south-west Scotland over the past 9,000 years."