From the end of the last Ice Age to the coming of the Romans: hunters on a vanished coastline, farmers who raised great stone tombs, and the hillforts of the Iron Age.
After the last Ice Age, small groups of hunter-gatherers moved through a landscape very different from today's. Sea levels were much lower, and woodland grew across land that is now under the sea.
As the ice melted and the sea rose, those forests were drowned. At very low tides, the dark stumps of ancient trees can still appear on Pembrokeshire beaches such as Amroth and Whitesands Bay — a glimpse of a lost coastline.
With farming came a new relationship with the land — and monuments built to last. Chambered tombs, or cromlechs, were raised from great slabs of stone, many of them in north Pembrokeshire.
Pentre Ifan, near Newport, is the most famous: a huge capstone balanced on slender uprights. Carreg Samson, near Abercastle, is another fine example. Both are thought to date from around 3500 BC.
Some of the smaller stones at Stonehenge, known as bluestones, have been traced to the Preseli Hills, more than 140 miles away.
Geologists have linked them to particular outcrops, including the spotted dolerite of Carn Goedog and rhyolite from Craig Rhos-y-felin. Exactly how they were moved, and why, is still debated — making the Preselis part of one of Britain's great prehistoric mysteries.
During the Bronze Age, people buried their dead beneath round cairns and barrows, often on high ground where they could be seen for miles. Standing stones were set up across the landscape.
Walkers on the Preseli ridge pass many of these monuments, still marking the skyline after thousands of years.
In the Iron Age, communities lived in defended settlements protected by banks and ditches. Pembrokeshire has many, from inland hillforts to dramatic promontory forts on the coast.
At Castell Henllys, roundhouses have been reconstructed on the site of an Iron Age fort, helping visitors imagine everyday life more than two thousand years ago.