A ritual burial appears more likely since the butter was not packed when it was interred at the site.
"These bogs in those times were inaccessible, mysterious places," Halpin told Press Association.
"It is at the juncture of three separate kingdoms, and politically it was like a no-man's-land -- that is where it all hangs together," he added.
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The finding is not unusual. Hundreds of packages of butter, some placed inside wooden boxes, have been retrieved from Irish bogs, along with exceptionally well-preserved wooden objects, swords and ornaments.
Such preservation is produced by the bogs' unique chemistry. The peat-building Sphagnum moss grows over anything tipped into the bog, embedding the buried material in cold, acid and oxygen-free conditions that immobilize bacteria, preventing decomposition.
The newly found butter is still edible – theoretically.
"But we wouldn't advice tasting it," Halpin said.