CNN  — 

Evidence of the earliest celebrations in Britain, which drew people and animals from hundreds of miles away, has been uncovered at four Late Neolithic complexes near Stonehenge – and pig was on the menu, according to a new study.

The UK henge complexes are some of the most studied and iconic prehistoric monuments in Europe, dating to between 2400 and 2800 BC. The earthworks served as ceremonial areas where resources and expenses weren’t spared. Close to the monuments of Stonehenge and Avebury, the four complexes are Durrington Walls, Marden, Mount Pleasant and West Kennet Palisade Enclosures.

Pigs were the animal of choice for feasting. The bones from 131 pigs were excavated at these sites, and researchers used isotope analysis to identify chemical signatures of the food and water the animals consumed to determine where they were from. Surprisingly, the animals came from as far away as Scotland, North East England and West Wales.

The study was published Wednesday in the journal Science Advances.

“These gatherings could be seen as the first united cultural events of our island, with people from all corners of Britain descending on the areas around Stonehenge to feast on food that had been specially reared and transported from their homes,” said Richard Madgwick, lead study author and lecturer in Cardiff University’s School of History, Archaeology and Religion, in a statement.

This means the animals had to travel hundreds of miles, and the researchers believe that people attending the celebrations needed to contribute animals they had raised where they lived. Otherwise, pigs were so common that they would have been easy to find close to these sites.

The researchers were also able to rule out the possibility that the pigs were slaughtered locally and brought to the celebrations as preserved pork. The skulls and limbs were still attached, there is no evidence for this kind of curing during the time period, and pork spoils more quickly than other meats and would have required a complex type of salting and smoking.

“Pigs are not nearly as well-suited to movement over distance as cattle and transporting them, either slaughtered or on the hoof, over hundreds or even tens of kilometres, would have required a monumental effort,” Madgwick said. “This suggests that prescribed contributions were required and that rules dictated that offered pigs must be raised by the feasting participants, accompanying them on their journey, rather than being acquired locally.”

The researchers believe that the findings reveal a detailed look at mobility during the peak of Stonehenge, which “demonstrate a level of interaction and social complexity not previously appreciated.”

Before, researchers debated where people traveled from to reach Stonehenge. The human remains that have been recovered there were cremated, which makes them much more difficult to study. But the human remains were determined to be nonlocal, which adds support to the idea of people and animals traveling long distances to reach these complexes, according to the new study.

This makes the henge complexes even more intriguing as sites where disparate groups from across Britain were united in feasting and celebrating, probably forging alliances and even bringing neighboring groups together as one. The Late Neolithic period was the first time in British prehistory where long-distance networks of people and livestock were created, the researchers said.