The earliest known human remain discovered in modern-day Wales is a human tooth, found in a cave in the valley of the River Elwy in North Wales, whose owner lived about 250,000 years ago in the Lower Palaeolithic period. The Red Lady of Paviland, a human skeleton dyed in red ochre, was discovered in 1826 in one of the Paviland limestone caves of the Gower Peninsula in south Wales. Despite the name, the skeleton is that of a young man who lived about 26,000 years ago at the end of the Upper Paleolithic Period (old stone age). He is considered to be the oldest known ceremonial burial in Western Europe. The skeleton was found along with jewellery made from ivory and seashells, and a mammoth's skull.
Following the last Ice age, Wales became roughly the shape it is today by about 8000 BC and was inhabited by Mesolithic hunter-gatherers. The earliest farming communities are now believed to date from about 4000 BC, marking the beginning of the Neolithic period. This period saw the construction of many chambered tombs, the most notable including Bryn Celli Ddu and Barclodiad y Gawres on Anglesey.
Metal tools first appeared in Wales about 2500 BC, initially copper followed by bronze. The climate during the Early Bronze Age (c. 2500-1400 BC) is thought to have been warmer than at present, as there are many remains from this period in what are now bleak uplands. The Late Bronze Age (c. 1400-750 BC) saw the development of more advanced bronze implements. Much of the copper for the production of bronze probably came from the copper mine on the Great Orme, where prehistoric mining on a very large scale dates largely from the middle Bronze Age.
The earliest iron implement found in Wales is a sword from Llyn Fawr at the head of the Rhondda Valley, which is thought to date to about 600 BC. The Iron Age saw the building of hillforts which are particularly numerous in Wales, examples being Pen Dinas near Aberystwyth and Tre'r Ceiri on the Lleyn peninsula. A particularly significant find from this period was made in 1943 at Llyn Cerrig Bach on Anglesey, when the ground was being prepared for the construction of a Royal Air Force base. The cache included weapons, shields, chariots along with their fittings and harnesses, and slave chains and tools. Many had been deliberately broken and seem to have been votive offerings.
Traditionally, historians have believed that successive waves of immigrants brought different cultures into the area, largely replacing the previous inhabitants, with the last wave of immigrants being the Celts. However, some studies of population genetics now suggest that this may not be true, and that the introduction of Celtic language in the Bronze Age may have been a result of immigration on a smaller scale.