A Scots religious site that predates the pyramids and Stonehenge may have been abandoned because of climate change, researchers claim.Kilmartin Glen, in Argyll, has one of the most important concentrations of Neolithic and Bronze Age remains in Europe. The glen contains at least 350 ancient monuments, many of them prehistoric, including burial cairns, rock carvings and standing stones. The most spectacular of the remains is the fortress of the Scots at Dunadd, capital of the kingdom of Dalriada.

But archaeologists have identified a period of almost 1,000 years in which no monuments were erected and the population there “diminished”. They claim this period is marked by the start of a colder, wetter climate.

Dr Alison Sheridan, an archaeologist and head of early prehistory at the National Museum of Scotland, who has studied Kilmartin Glen for more than 20 years, said:”The earliest activity dates back to hunter-gatherers around 4,500BC, who left behind nothing more than a few pits, charcoal and some flint. It was a sacred landscape from at least as early as 3,700BC until as late as 1,100BC. It was a place for ceremony, for burying people and observing the movements of the sun and the moon.We are not too certain what happened between 1,100BC and around 200BC. A hoard of swords has been found and a few artifacts buried as gifts to the gods in the late Bronze Age between 1,000 and 750BC. But there are very few structures and no settlements.Certainly, in some parts it seems to have become colder and wetter after about 1,200BC, and the people may have moved away.”

Kilmartin Glen was home to self-sufficient and successful communities with links around the country and even overseas. Historic monuments include standing stones, a henge, a linear cemetery comprising five burial cairns and numerous cists, or stone coffins, which contained remains of adults and children as young as four.

Neal Ascherson, visiting Professor at the Institute of Archaeology, University College London, said climate change brought an end to “this strange, idyllic period of late Neolithic and Bronze Age in this area”.He said: “The weather, which was dryer and finer than it is now, seems to have come to an end around 1,000BC, when it began to change and the whole ecology began to alter. At the same time, culture changed.The capacity or wish to build these monuments and indeed to honour them or take account of them, died away. And in the Iron Age nobody took much account of these monuments and certainly nobody tried to build anything of the kind again. Instead, you get a quite different culture in which you get tiny fortified settlements and you feel everything is colder and more hostile. The population diminished heavily, but whoever was left seemed to fear everyone else.”

Sharon Webb, the curator of the Kilmartin Museum, said: “When the first people moved in to this landscape it would have been a landscape of plenty. The rivers and lochs would have been teeming with fish, the woods would have been full of game and there were lots of plants they could have eaten – nettles, berries and fungi in the forests. It was a really rich place for the hunter-gatherer people to find enough resources to live.”