The Perdigões Research Program blog mentions a new study where the structure is dissected through time, revealing it as a meeting area (with whatever ritual implications) for the Neolithic and Chalcolithic peoples of that area of the Alentejo near the Guadiana river.
A.C. Valera, A.M. Silva & J.E. Martínez Romero, THE TEMPORALITY OF PERDIGÕES ENCLOSURES: ABSOLUTE CHRONOLOGY OF THE STRUCTURES AND SOCIAL PRACTICES. SPAL Revista de Prehistoria y Arqueología, nº23, 2014. Freely accessible → LINK [doi:10.12795/spal.2014i23.01]
Abstract: Thirty five radiocarbon dates for the Neolithic and Chalcolithic ditched enclosure of Perdigões (Reguengos de Monsaraz, Portugal) are presented. After a discussion of some of the problems of dating negative structures, a chronological sequence is presented for the ditch structures and for the social practices related to funerary behaviours and the manipulation of human remains. A clear Neolithic phase is identified, well separated chronologically from the Chalcolithic one. The possibility of the gradual and eventually interrupted development of the site, is discussed. Funerary contexts and the manipulation of human remains are present from the earliest phase of the site, but the practices became significantly diverse during the 3rd millennium by the end of which the site seems to decay and significant activity seems to stop.
|Fig. 5 (red highlights are mine)|
To the right we can see fig. 5 of the paper ("Representation of the actual understanding of the chronological development of Perdigões"), just that I have highlighted with red paint the elements known to be active in each period, because I felt that black vs grey was not visible enough.
Regarding the cromlech (stone ring, represented as a circle to the right), lead author Antonio Valera commented at the Perdigões Research Program blog that they are not yet 100% certain of its age, although he does believe it is from the earliest context. That's what I marked it with a dotted line instead of a continuous one.
This cromlech was one of the items that interested me the most because in other contexts, as happens with Pyrenean ones, they are historically known in some cases to have been reference sites for community meetings (the local constituent power), but here they are from the Iron Age.
It is notable that, in the historical cases from the Pyrenees, the meetings did not take place inside the cromlechs themselves (usually too small and occasionally burial sites) but near them. Similarly in this case of Perdigões the meeting (and possibly ritual) area defined by the ditches is located by the cromlech, west of it specifically.
Later on two tholoi (beehive tombs, typical of Chalcolithic South Iberia) were built near the cromlech, being eventually enclosed by the last and largest ditch.
The chronological pattern also suggests the idea of growth: if the structure was being made bigger and bigger, it seems logical to think that it was because the community using it was also growing, what should not be any surprise.
The site was abandoned at the end of the 3rd millennium BCE. At that time SW Iberia was experiencing significant changes with the abandonment of urban centers and other traditions like these Megalithic ones, and being replaced by a sequence of (seemingly intrusive) Bronze Age "horizons" dominated by burials in cist with a triangular bronze knife as most characteristic grave good and occasional "grabsystem" tombs, probably of princely character. These Bronze Age "horizons" expanded from the Algarve to the North and Northeast up to approximately the Tagus river at their apogee, being maybe ancestral to the mysterious Tartessian language, which spanned approximately the same area in the Iron Age.