Archaeological evidence from some Neolithic sites (e.g. Tinkinswood) has shown the continued use of cromlechi in the Bronze Age. The Bronze Age – defined by the use of metal – has made a lasting impression on the area. Over six hundred Bronze Age barrows and cairns, of various types, have been identified all over Glamorgan. Other technological innovations – including the wheel; harnessing oxen; weaving textiles; brewing alcohol; and skillful metalworking (producing new weapons and tools, and fine gold decoration and jewellery, such as brooches and torcs) – changed people's everyday lives during this period. Deforestation continued to the more remote areas as a warmer climate allowed the cultivation even of upland areas.By 4000 BP people had begun to bury, or cremate their dead in individual cists, beneath a mound of earth known as a round barrow; sometimes with a distinctive style of finely decorated pottery – like those at Llanharry (discovered 1929) and at Llandaff (1991) – that gave rise to the Early Bronze Age being described as "Beaker culture". From c. 3350 BP, a worsening climate began to make agriculture unsustainable in upland areas. The resulting population pressures appear to have led to conflict. Hill forts began to be built from the Late Bronze Age (and throughout the Iron Age (3150–1900 BP)) and the amount and quality of weapons increased noticeably – along the regionally distinctive tribal lines of the Iron Age. Archaeological evidence from two sites in Glamorgan shows Bronze Age practices and settlements continued into the Iron Age. Finds from "Llyn Fawr", thought to be votive offerings, include weapons and tools from the Late Bronze Age and the Early Iron Age. The hoard, described as "one of the most significant prehistoric metalwork hoards in Wales" has given its name to the Llyn Fawr Phase, the last Bronze Age phase in Britain. Excavations at Llanmaes, Vale of Glamorgan, indicate a settlement and "feasting site" occupied from the Late Bronze Age until the Roman occupation. Until the Roman conquest of Britain, the area that would become known as Glamorgan was part of the territory of the Silures – a Celtic British tribe that flourished in the Iron Age – whose territory also included the areas that would become known as Breconshire and Monmouthshire. The Silures had hill forts throughout the area – e.g., Caerau (Cardiff), Caerau hill fort, Rhiwsaeson (Llantrisant), and Y Bwlwarcau [Mynydd Margam, south west of Maesteg – and cliff castles along the Glamorgan coast – e.g., Burry Holms (Gower Peninsula).