People have lived in and around what is now Asti since the Neolithic period. Before their defeat in 174 BC by the Romans, tribes of Ligures, the Statielli, dominated the area and the toponym probably derives from Ast which means ”hill” in the ancient Celtic language.

In 124 BC the Romans built a castrum, or fortified camp, which eventually evolved into a full city named Hasta. In 89 BC the city received the status of colonia, and in 49 BC that of municipium. Asti become an important city of the Augustan Regio IX, favoured by its strategic position on the Tanaro river and on the Via Fulvia, which linked Derthona (Tortona) to Augusta Taurinorum (Turin). Other roads connected the city to the main passes for what are today Switzerland and France.

The city was crucial during the early stages of the barbarian invasions which stormed Italy during the fall of the Western Roman Empire. In early 402 AD the Visigoths had invaded northern Italy and were advancing on Mediolanum (modern Milan) which was the imperial capital at that time. Honorius, the young emperor and a resident in that city, unable to wait for promised reinforcements any longer, was compelled to flee from Milan for safety in the city of Arles in Gaul. However, just after his convoy had left Milan and crossed the River Po his escape route through the Alps was cut off by the Gothic cavalry. This forced him to take emergency refuge in the city of Hasta until more Roman troops could be assembled in Italy. The Goths placed Hasta under siege until March when General Stilicho, bringing reinforcements from the Rhine, fought and defeated them at the Battle of Pollentia. After this first victorious defence, thanks to a massive line of walls, Hasta suffered from the barbarian invasions which stormed Italy after the fall of the Western Empire, and declined economically.