I'll reduce this down a bit. Beaker pottery, such as the Palmela Group and the Incised Group, were at one time thought to have followed an evolutionary format with the Maritime AOO "International" Style influencing local potteries (or being influenced by) resulting in new regional beaker styles. However, it is shown that these three beakers are all very old and coexist around the Tagus and their distribution corresponds with space rather than time.
|Castro do Zambujal - JuTa|
Essentially, the primary focus here is the cultural development within the Estremadura, which is the land above the Tagus Estuary (the heart of Portugal). The Estremadura has the highest concentration of Bell Beaker artifacts in the Iberian Peninsula to date, and both the bay area and these lands were very important in the emergence of the Bell Beaker phenomenon and its spread elsewhere.
It may be that several groups were targeting key terrain and watercourses in Iberia at this time, especially the mouth of the Tagus.
The complexity of the Beaker phenomenon in the Tagus estuary does not fit well with the model of three successive groups (International, Palmela and Incised Groups). The above seems to result from the nature of the settlements rather than from its chronology, as all three groups are present during the second half of the 3rd millennium BC. Therefore while artifacts of the International Group predominate in the fortified sites, the Incised Group appears almost exclusively in open sites. The Palmela Group seems of minor importance, at least in the north region of the Tagus River estuary. The remarkable antiquity of Beaker pottery found in the FM hut at Leceia (which dates from the 2nd quarter of the 3rd millennium BC, re-confirmed by AMS dating) has parallels both in the North and South of Portugal, as well as in Spain. Thus we conclude that in the Lower Estremadura (one of the most important regions in Europe for the discussion of the origin and diffusion of Beaker “phenomenon”), the Beaker social formation with its own distinct cultural characteristics, coexisted with local Chalcolithic cultures, although never merged with them.
Absolute chronology of the Beaker phenomenon North of the
Tagus estuary: demographic and social implications (João Luís Cardoso, 2014) [link]
Some background [link]