The oldest traces of hominid existence in Switzerland date back about 150,000 years.The oldest known farming settlements in Switzerland, which were found at Gächlingen, have been dated to around 5300 BC.
The earliest known cultural tribes of the area were members of the Hallstatt and La Tene cultures, named after the archaeological site of La Tène on the north side of Lake Neuchatel. La Tene culture developed and flourished during the late Iron Age from around 450 BC,possibly under some influence from the Greek and Etruscan civilisations. One of the most important tribal groups in the Swiss region was the Helvetii. Steadily harassed by the Germanic tribes, in 58 BC the Helvetii decided to abandon the Swiss plateau and migrate to western Gallia, but Julius Caesar's armies pursued and defeated them at the Battle of Bibracte, in today's eastern France, forcing the tribe to move back to its original homeland.In 15 BC, Tiberius, who would one day become the second Roman emperor, and his brother Drusus, conquered the Alps, integrating them into the Roman Empire. The area occupied by the Helvetii - the namesakes of the later Confoederatio Helvetica - first became part of Rome's Gallia Belgica province and then of its Germania Superior province, while the eastern portion of modern Switzerland was integrated into the Roman province of Raetia. Sometime around the start of the Common Era, the Romans maintained a large legionary camp called Vindonissa, now a ruin at the confluence of the Aare and Reuss rivers, near the town of Windisch, an outskirt of Brugg.
The first and second century AD was an age of prosperity for the population living on the Swiss plateau. Several towns, like Aventicum, Iulia Equestris and Augusta Raurica, reached a remarkable size, while hundreds of agricultural estates (Villae rusticae) were founded in the countryside. Around 260 AD, the fall of the Agri Decumates territory north of the Rhine transformed today's Switzerland into a frontier land of the Empire. Repeated raids by the Alamanni tribes provoked the ruin of the Roman towns and economy, forcing the population to find shelter near Roman fortresses, like the Castrum Rauracense near Augusta Raurica. The Empire built another line of defence at the north border (the so-called Donau-Iller-Rhine-Limes), but at the end of the fourth century the increased Germanic pressure forced the Romans to abandon the linear defence concept, and the Swiss plateau was finally open to the settlement of Germanic tribes.
In the Early Middle Ages, from the end of the 4th century, the western extent of modern-day Switzerland was part of the territory of the Kings of the Burgundians. The Alemanni settled the Swiss plateau in the 5th century and the valleys of the Alps in the 8th century, forming Alemannia. Modern-day Switzerland was therefore then divided between the kingdoms of Alemannia and Burgundy. The entire region became part of the expanding Frankish Empire in the 6th century, following Clovis I's victory over the Alemanni at Tolbiac in 504 AD, and later Frankish domination of the Burgundians.
Throughout the rest of the 6th, 7th and 8th centuries the Swiss regions continued under Frankish hegemony (Merovingian and Carolingian dynasties). But after its extension under Charlemagne, the Frankish Empire was divided by the Treaty of Verdun in 843.The territories of present-day Switzerland became divided into Middle Francia and East Francia until they were reunified under the Holy Roman Empire around 1000 AD.
By 1200, the Swiss plateau comprised the dominions of the houses of Savoy, Zähringer, Habsburg, and Kyburg.Some regions (Uri, Schwyz, Unterwalden, later known as Waldstätten) were accorded the Imperial immediacy to grant the empire direct control over the mountain passes. With the extinction of its male line in 1263 the Kyburg dynasty fell in AD 1264; then the Habsburgs under King Rudolph I (Holy Roman Emperor in 1273) laid claim to the Kyburg lands and annexed them extending their territory to the eastern Swiss plateau.
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