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Though the stones were only erected in 2500 B.C. there are evidences of burials since 3000 B.C.
It seems like the local was used to only bury elements of one family being the first one at 3000 B.C. and then as the family gown up more and more bodies were then buried afterwards.
At the time bodies used to be cremated and methods of rating how old were those cremated bones just came to the access of researchers allowing the recent dating of the remains found at Stonehenge.
British archaeologists say it probably was a cemetery for the ruling dynasty responsible for erecting Stonehenge.
The answer to why researchers found up to 240 people remains is because Stonehenge staged as burial place for several generations of the same single elite family. The clue comes from the small number of burials in the earliest period and the larger numbers in the later centuries, as offspring would have multiplied said Andrew Chamberlain, Sheffield archaeologist.