The authors agree that this is a surname of ethnic origin, linked to the geographical provenance of the first bearers: "inhabitant or native of Tuscany". F. Miranda specifies that the place name refers to the Latin Tuscia or Etruria, the names by which that region was historically known.

E. De Felice notes that the surname was formed from the patronymic Toscano or Tosco, and that its greatest frequency occurs in Campania and Calabria. He also points to regional variants: Tuscano and Toscanese are typical of southern Italy, while Toscan appears in Veneto and in Friuli-Venezia Giulia; in Emilia-Romagna the form Tosco predominates, very frequent under the variant Toschi.

Miranda broadens the geographical distribution: the surname is typical of the centre-south, with a particular concentration in Sicily, Campania and Calabria, though it is present throughout Italy, including Lombardy, Lazio, Piedmont, Liguria and Tuscany itself. In Sicily it appears diffused especially in the Catania, Messina, Palermo, Syracuse and Enna areas, with a lesser presence in the Agrigento, Caltanissetta, Trapani and Ragusa areas.