The history of the area stretches back up to 10,000 years; there are 22 Mesolithic sites in Tameside, the oldest dating to around 8000 BC; 21 of the 22 sites are in the hilly uplands in the north east of the borough. Evidence of Neolithic and Bronze Age activity is more limited in the borough, although the Bronze Age Stalybridge Cairn is the most complete prehistoric funerary monument in the borough. The people in the area changed from hunter-gatherers to farmers around 2500 BC–1500 BC due to climate change. Werneth Low is the most likely Iron Age farmstead site in the borough, probably dating to the late 1st millennium BC. Before the Roman conquest of Britain in the 1st century AD, the area was probably part of the territory of the Brigantes, the Celtic tribe controlling most of what is now north west England.