The central six-ton altar stone at Stonehenge may have come from more than 450 miles away, according to a new study published in the scientific journal Nature.

Stonehenge is thought to have been erected in several phases between 3100 BCE and 1600 BCE, with the circle of large sarsen stones placed there between 2600 BCE and 2400 BCE by Neolithic and Bronze Age people. While larger local stones may have been moved by hundreds of individuals with ropes and log rollers, the Welsh bluestones could have been transported by sea using rafts.

Researchers have already established that the sarsen stones came from 16 miles away from the site, in what is now the British town of Marlborough, and that the smaller bluestones were brought in from 125 miles away, from the Preseli hills in what is now Wales.

Until now, it was believed that the partially buried altar stone came from the same area in Wales. But this latest study suggests that the center stone is from the old red sandstone in the Orcadian Basin in Northeast Scotland, more than 450 miles away.

The study was conducted by researchers from Aberystwyth University, University College London, Curtin University, and the University of Adelaide. The source of the stone, they believe, is a region that includes the Orkney isles, John O’Groats in Caithness, and a narrow strip along the coast that extends to the Moray Firth around Inverness.

“This is a really intriguing development that makes us think again about how connected people were in the Neolithic, and what feats they were capable of achieving. Research into Stonehenge is always evolving our understanding of the site. It’s very exciting to have a possible connection to the Highlands and Islands, where we also have incredible Neolithic monuments,” Lynne McKeggie, the director of Highland Archaeology Services, told the Art Newspaper.