 They cleared the forests to establish pasture and to cultivate the land, developed new technologies such as ceramics and textile production, and built cromlechs such as Pentre Ifan, Bryn Celli Ddu and Parc Cwm long cairn between about 5,800 BP and 5,500 BP.Over the following centuries they assimilated immigrants and exchanged ideas of the Bronze Age and Iron Age Celtic cultures.According to John T. Koch and others, Wales in the Late Bronze Age was part of a maritime trading-networked culture that also included the other Celtic nations.