The name of the small town, probably comes from the Latin asinus (donkey); indeed, in the past, the surrounding countryside was full of farmers who raised donkeys; hence it was called Asinaia. Some argue, however, that the name may derive (like Siena) from the Hebrew "Sen" which means peak, high ground, or from "Sepu" which translated is: irrigated. Indeed the area is rich in water; also the latter case would justify the other name by which the fraction is called, that is Sepaia.

The village consists of a few houses, built of stone of Tuscan origin, who have been joined by other newly built. The place does not have a church nor its cemetery, but it is located along the road to the Sanctuary of the Madonna of Bagno and near the abbey of Sant'Andrea al Pozzo della Pieve in Retina and the suppressed convent of St. Christopher. The road leading to the Sanctuary of Madonna of Bagno has been enriched by fifteen tabernacles, built in 1988 by the artist Tommaso Musarra, each depicting a Mystery of the Rosary, so as to allow for those who want to bear walking from Castiglion Fiorentino to the Madonna del Bagno, to recite the entire crown, stopping at every station.

The sanctuary of the Madonna of Bagno is located at the point where, according to Catholic tradition, the Virgin appeared and from where a source gushed curative water. Initially it was a small oratory that was replaced, between 1524 and 1527, from a building that remained unfinished. It was enlarged in 1711, but the current building, a Latin cross with a vaulted ceiling, was reconstructed in the years 1874-87 by the architect Pietro Mancini of Castiglion Fiorentino.