The source of the Esino River rises in the city of Esanatoglia.
The famous valley of Esino was once described by Gonfalonieri di Ancona e Jesi (in the beggining of XX century) as "…surrounded by the always fertile and smiling hills, with plenty of villages, castles and people, all industrialised, cultivated and abundant of commercial products."
The central position it takes across the territory would not be enough to elevate this valley as the most important in the region if History had not repeatedly placed the Esino river in the geographical borders of different areas; in the antiquity the river divided the Ager Gallicus to the north from the Picenum to the south.
Similar division occurs from VII century to the establishment of the Holy Roman Empire, when in the Esino river settled the Bizantine and the Longobards.
While the Pentapoli Annonaria (Urbino, Fossombrone, Cagli, Gubbio, Jesi) was all in the North, the Pentapoli Marittima (Rimini, Pesaro, Fano, Senigallia, Ancona) as the Doric center was in the South of the River and therefore in direct contact with the Longobards of Ducato di Spoleto who, having Camerino as a second capital, could control both the front and the dorso of the Apenines hills.
The Esino river also creates a demarcation line in the course of History when, with regional organisation under Emperor Augustus, the river served as border line between Umbria and Piceno, which remains alive until today in the linguistic evolution of dialects along the Esino and in between the Celtic and Italian elements.