The surname has independent origins in different regions of Italy, with a predominant presence in Sardinia and a secondary concentration in Sicily. E. Rossoni notes that in Sardinia it is distributed across the whole island, with notable clusters in Cagliari, Sassari, the Iglesiente, and the provinces of Oristano and Nuoro. In Sicily, Rossoni documents it at Caltanissetta, Favara, Palermo, Catania, Cerami, and in the province of Messina.

Regarding the etymology of the Sardinian stock, Rossoni traces the surname to a nickname derived from the Sardinian term milìa, meaning "bleating," possibly used to identify an ancestor devoted to herding. F. Miranda adds a second hypothesis: the term could instead come from the Greek milìa, with the meaning "apple tree." A separate etymology is proposed by the source Surnames in Italy, which considers the surname to derive from the personal name Emilio.

Miranda broadens the geographic picture for Sicily, recording a presence in the provinces of Agrigento, Caltanissetta, Palermo, Messina, Catania, and Trapani. He further specifies that in the area of Enna the surname is attested in the municipalities of Agira, Regalbuto, Cerami, and Pietraperzia. Miranda also notes that the surname appears in several other regions of Italy, including Lombardy, Lazio, Piedmont, Tuscany, Liguria, Calabria, and Emilia-Romagna.