It is an important industrial and artistic center in the floodplain on the left (north) bank of the Esino river 17 kilometres (11 mi) before its mouth on the Adriatic Sea.

Jesi was one of the last towns of the Umbri when, in the 4th century BC, the Senones Gauls invaded the area and ousted them. They turned it into a stronghold against the Piceni. In 283 BC the Senones were defeated by the Romans. Jesi in 247 BC became a colonia civium romanorum with the name of Aesis.

During the fall of the Western Roman Empire, Iesi was ravaged by the troops of Odoacer (476 AD) and again in 493 by the Ostrogoths of Theodoric the Great. After the Gothic War, Italy became part of the Byzantine Empire, and Jesi became one of the main centers of the new rulers, and also became a diocese seat. In 751 it was sacked by the Lombard troops of Aistulf, and later was a Carolingian imperial city.

Starting from 1130, it was an independent commune, gradually expanding in the neighboring countryside. In December 1194 it was the site of the birth of Holy Roman Emperor Frederick II, who later gave it the title of "Royal City". In the 14th century it was captured by the Papal vicar Filippo Simonetti, by Galeotto I Malatesta (1347–1351), by Braccio da Montone in 1408, and by Francesco I Sforza, who turned it into his family's main stronghold in the Marche. In 1447 it was bought by the Papal States.

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