As in neighbouring Vaud, Julius Caesar was an early 'tourist' in these parts. Historians fail to record whether he packed his skis, but we do know the Roman leader brought an army to conquer the Celtic community living in the valley, penetrating as far as Sierre. Once under Roman domination, it appears the four Celtic tribes of the Valais were peaceably integrated into the Roman system. Artefacts and archaeological remains still attest to the passage of the rambling general and his boys from Rome.
Sion became a key centre in the valley when the Bishop of Valais blessed the town with his presence, making his home there from AD 580. By 1000, the bishop's power stretched from Martigny to the Furka Pass.
That power did not go uncontested. A succession of Dukes of Savoy managed to encroach on the bishops' territory and a Savoyard army besieged Sion in 1475. With the help of the Swiss Confederation, the city was freed at the battle of Planta. Internal opposition was just as weighty and the independently minded communes that made up the Valais region stripped the bishops of their secular power in the 1630s, shifting the levers of control into the hands of the Diet, a regional parliament.
The Valais was not invaded again until Napoleon Bonaparte called by in 1798. The little man with big plans was determined to dominate the routes into Italy. Valais joined the Swiss Confederation in 1815.