For some time, first based in the aerial photograph and later based on the magnetogram, it was though that configuration of space was created to receive the necropolis.
Well, radiocarbon dating is showing something else. The first uses of the two excavated tombs are dated from the first half of the third millennium BC, while the filling of the outside ditch is from the third quarter of that same millennium, suggesting that when the ditch was open the tombs were already there.
It seems now that the presence of the tombs is responsible for the curve of the ditch. What exactly they intended by that? Respect the previous holy ground? A need of enclosure that specific symbolic area that might still in use?
Well, maybe both, since archaeological contexts and radiocarbon dating also show that one of the tombs was reused precisely during the third quarter of the third millennium.
But this is just a later episode of the funerary practices that took place at Perdigões.
References:Valera, A.C., Silva, A.M. & Márquez Romero, J.H., “Temporality at Perdigões enclosures: absolute chronologies of structures and practices”, paper presented at the VI Archaeological Meeting of Southwest Iberia, 2012, in preparation for publication.