(CNN) — The Stonehenge altar stone, located at the heart of the ancient monument in southern England, was probably transported over 700 kilometers from what is now northeast Scotland almost 5,000 years ago, according to new research.

The results of a new study published Wednesday in the journal Nature disprove the centuries-old idea that the Altar Stone came from what is now Wales. The Altar Stone, the largest of the bluestones used in the construction of Stonehenge, is a thick block that weighs 6 tons and lies at the center of the stone circle.

“This stone has travelled an awfully long distance – at least 700km – and that is the longest recorded journey for a stone used in a monument during this period,” study co-author Nick Pearce, a professor in the department of geography and earth sciences at Aberystwyth University in Wales, said in a statement. “The distance travelled is astonishing for the time.”

The research directly addresses one of Stonehenge’s many mysteries and also opens new ways of understanding the past, including the connections between Neolithic people who left no written records, the study authors said.

According to researchers, construction of Stonehenge began as early as 3000 BC and occurred in several phases. The altar stone is said to have been inserted into the central horseshoe during the second construction phase between 2620 and 2480 BC.

The discovery of the stone’s origin suggests that ancient Britain and its inhabitants were far more advanced and capable of moving large stones, possibly with the help of maritime transport, the study authors wrote.

Deciphering ancient secrets

Extensive research has focused on the types of stone used to build the iconic Wiltshire circle over the years, and previous analysis has shown that bluestones, a type of fine-grained sandstone, and silicified sandstone blocks called sarsens were used in the construction of the monument. The landmark sits on the southern edge of Salisbury Plain, which was inhabited as far back as 5,000 to 6,000 years ago.

The sarsen stones come from the West Woods near Marlborough, about 25 kilometres away, while some of the bluestones come from the Preseli Hills area of ​​West Wales and are believed to be the first stones placed on the site. Researchers have included the Altar Stone among the bluestones, but its origins have remained a mystery until now.

“Our discovery of the origins of the Altar Stone highlights a significant level of societal coordination during the Neolithic period and helps paint a fascinating picture of prehistoric Britain,” study co-author Chris Kirkland, professor and head of the Timescales of Mineral Systems Group in the School of Earth and Planetary Sciences at Curtin University in Australia, said in a statement.

“Transporting such a massive cargo overland from Scotland to southern England would have been extremely difficult, suggesting a likely shipping route along the coast of Britain. This suggests long-distance trade networks and a higher level of social organisation than is generally thought to have existed in Britain during the Neolithic period.”

To better understand the origin of the altar stone, researchers analyzed the age and chemical composition of mineral grains from fragments of the stone itself.

Analysis showed that the fragments contained zircon, apatite and rutile grains. The zircon was dated to be between 1 and 2 billion years old, while the apatite and rutile grains date back to between 458 and 470 million years ago.

The team used age analysis of the mineral grains to create a “chemical fingerprint” that could be compared to sediments and rocks across Europe, said lead study author Anthony Clarke, a PhD student in the Timescales of Mineral Systems Group in the School of Earth and Planetary Sciences at Curtin University. The grains best matched a group of sedimentary rocks known as the Old Red Sandstone, found in the Orcadian Basin in northeast Scotland, which were completely different from the rocks found in Wales.

“The finds raise fascinating questions about how such a massive stone could have been transported over long distances in 2600 BC, given the technological limitations of the Neolithic period,” Clarke said.

For Clarke, the discovery was also personal, as he grew up in the Preseli Hills in Wales, where some of the stones of Stonehenge lie.

“I first visited Stonehenge when I was one year old and now, at 25, I have returned from Australia to help with this scientific discovery – you could say the stone circle has brought me full circle,” Clarke said.

But the discovery that the altar stone comes from what is now Scotland raises a number of new questions.

“It is exciting to know that our chemical analysis and dating work have finally solved this great mystery,” study co-author Richard Bevins, honorary professor in the department of geography and earth sciences at Aberystwyth University, said in a statement. “The hunt will continue for a long time to find out exactly where in northeast Scotland the altar stone came from.”

Joshua Pollard, professor of archaeology at the University of Southampton, called the discovery a “great result.” Pollard was not involved in the investigation.

“The science is good,” Pollard said. “This is the team that successfully found the smaller Stonehenge bluestones using a number of fairly sophisticated techniques.”

Moving massive stones

Today the Altar Stone lies broken on the ground, with two stones from the collapsed Great Trilithon structure resting on top of it. A trilithon is a pair of vertical stones with a horizontal stone resting on top. The horseshoe shape of Stonehenge consists of five trilithons, but the Great Trilithon was aligned with the solstice axis, so at the winter solstice the sun appeared to set between the two stones.

However, researchers doubt whether the altar stone once stood upright and what purpose it once served.

“One suggestion is that stones were a testimony to the dead and that Neolithic people therefore built stone circles as part of their rituals to honor their ancestors,” Bevins said.

Pollard described the altar stone as a kind of “anomaly, located in what should be the most sacred part of the monument.”

But how exactly did the huge altar stone end up on Salisbury Plain?

At the time, Britain was covered in forests and other impassable geography that would have made transporting the stone over land incredibly difficult, the study authors said. However, a sea route would have made transport across the sea possible, Clarke said.

“Although it seems incredible, Stonehenge itself is an incredible monument,” Pollard said. “It’s looking more and more like the stones came from sources that are the ancestors of those who created Stonehenge – it sort of condenses historical lineages into one place.”

There are other examples of the transport of animals, objects and stones that suggest that cargo was shipped over open water during the Neolithic period, the authors wrote in the study. Stone tools have been found throughout Britain, Ireland and continental Europe, including a large stone grinding tool found in the county of Dorset, which comes from what is now Normandy.

There is also evidence that shaped sandstone blocks were transported on rivers in Britain and Ireland.

“Although it was not the aim of our new empirical research to answer the question of how it got there, there are obvious physical obstacles to transport over land but a daunting journey over the sea,” said Pearce. “There is no doubt that this Scottish source reveals a high level of societal organisation in the British Isles during this period. These findings will have enormous implications for understanding Neolithic communities, their level of interconnectedness and their transport systems.”

The authors agreed that some questions about Stonehenge may never be answered.

“We know why many ancient monuments were built, but the purpose of Stonehenge will always remain unknown,” Clarke said. “And that’s why we must turn to the rocks. It is an enduring mystery.”

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