the historical period about 3 000 years ago when people first used iron tools CultureIron Age BritainAt the end of the Bronze Age iron began to be used instead of bronze (= a mixture of copper and tin) for making tools and weapons. Iron tools were harder and more efficient, and also cheaper. Bronze came to be used only for decorated items such as bowls or brooches.In Britain the Iron Age began about 500 BC. Some time before this, Celts had begun arriving in the British Isles from Europe and had mixed with the people already living there. Some were farmers and grew wheat and beans, and kept animals. The Celts are best known for their metalwork, and there is archaeological evidence of metal workshops in southern England and near Grimsby on the east coast. There was a trading centre at Hengistbury Head near Bournemouth until the middle of the 1st century BC. Metal items such as weapons and jewellery were made near there and sold in Britain and abroad. Iron bars were used as currency before coins were introduced in the 1st century BC. Pieces of pottery indicate that at the same time food and wine were imported from France.Hill forts such as that at Maiden Castle in Dorset were the headquarters of local chiefs and centres of administration, craftwork and trade for their tribes, as well as being used for defence. Hill forts covered a large area of land, usually on top of a hill, and were surrounded by ditches (= long, narrow channels dug in the ground) and earth ramparts (= banks) with a wooden fence on top. Inside were round thatched houses, workshops and grain stores. Each hill fort also had a shrine or religious building.The Celtic tribes, now often called the ancient Britons, were defeated when the Romans invaded Britain in 43 BC. After peace was established the hill forts were no longer used, though some were later repaired and used for defence against the Anglo-Saxons in the late 5th century. In the Roman period new artistic influences came to southern Britain and many Celtic chiefs adopted Roman ways. Further north and west, the Celts fought to remain outside the Roman province of Britannia. The Iron Age ended in England and Wales during Roman times, but little is known of the Celtic regions further north until their culture reached its highest point of achievement in the 7th and 8th centuries.