Prior to the Celts, the Beaker folk arrived in Britain around 2700-2500 BC, intermingling fairly peacefully with the existing Neolithic culture and adopting its henges. They brought new burial practices with them so that Neolithic long barrows or cairns were replaced by smaller barrows or tumuli. They also brought new metalworking techniques with them, in copper and gold. They came from a society that stretched across Europe (covering all of Iberia, most of Germany, and northern and southern France excluding the Central Massif).
The Beaker folk introduced a patriarchal society in which the individual warrior-chieftain became the most important and powerful figure, replacing the existing egalitarian society that built Stonehenge. They gained their name, which is sometimes given as Bell Beaker Folk, through their use of a large number of drinking cups called beakers. Burials with these pots alongside the dead have been used by archaeologists to chart the growth and expansion of the Beaker folk
Their arrival was not an invasion of new people, the Beaker folk were an influx of a new ruling elite in much the same way as later waves of Celtic arrivals. They were farmers and archers, wearing stone wrist guards to protect their arms from the sting of the bowstring. It was actually the Beakers who introduced the roundhouse, which echoed in shape both the henges and barrow mounds, made their own, distinctive, pottery, and produced the first woven garments in Britain. They also introduced the first known alcoholic drink, a form of honey based mead. They were emulated by the natives, so within a fairly short period everyone were Beaker folk, newcomers and natives alike.
The first wave of Celtic settlers in Britain arrived in the Late Bronze Age period, between 1500 BC at the earliest to around 1000 BC. Like the Beaker folk, they were peaceful settlers. These early Celtic arrivals were later the focus of what may have been a long-established tradition of kingship that was claimed by the post-Roman Celtic peoples of Britain.
These early arrivals were rulers of the British Celtic tribes (starting initially in the south and east of Britain and working northwards). They were the strongest rulers of their own tribal groups and held at high-kingship over the rest. Their duty as high king was exercised to unite tribes in times of emergency, such as at the landings of Julius Caesar in 55 and 54 BC. History shows that both kings and queens ruled over various tribes.
They would train with the warriors of their tribes and lead them into battle, but only to protect their tribes. The Celts were fierce warriors, but only as protectors of their tribes and the kingdom.