Following the last ice age, Wales became roughly the shape it is today by about 8000 BC and was inhabited by Mesolithic hunter-gatherers. The earliest farming communities are now believed to date from about 4000 BC, marking the beginning of the Neolithic period. This period saw the construction of many chambered tombs particularly dolmens or "cromlechs". The most notable examples of megalithic tombs include Bryn Celli Ddu and Barclodiad y Gawres on Anglesey, Pentre Ifan in Pembrokeshire, and Tinkinswood Burial Chamber in the Vale of Glamorgan.