Sorry if this is a silly question. Italy comes from the name of a region near Calabria and was expanded by the Romans to refer to the whole peninsula up to the Alps, but what was the entire peninsula called before that? I've heard Hesperia/Esperia, but can't find any source to prove it. Thanks for any answers.
Italy as a definite geographic space first occurs in Herodotus, actually, at 1.24. For Herodotus, if you map out the places he refers to as Italy, it's pretty clear the term refers to just the Greek-settled coast around the Gulf of Taranto. The late 5th century historian Antiochus extended his definition of Italy further inland, and Strabo took it up to the Gulf of Salemo. It wasn't until probably in 42 BCE, that the term came to include the whole peninsula between the Straight of Messina and the Alps, although there was a close association between the Alps and the rest of the peninsula as early as Cato the Elder.
The Greek writers don't show a lot of consciousness of the peninsula as a geographical unit, and have different names for different parts of the peninsula that falls outside the definition of "Italy" a particular author uses. The south-west coast, or parts of it might be called Oenotria, while the south-east might be called Iapygia, and so on for as far as the Greeks had knowledge of the peninsula.
On the Latin side, Cato (our first prose Latin author, writing around 200 BCE) seems to have used a very broad definition of Italy and, as I said, even makes a close association of Italy to the Alps (he calls the Alps the "shield of Italy;" people argue about whether that meant to include them inside "Italy" or not). Politically, as I said, Cisapline Gaul remained outside Italy, governed as a province, until Octavian arranged for the ratification of Caesar's acts and caused them to be put into full effect, probably 42 BCE.
Hesperia is "land in the west" in Greek, and was used by Stesichorus in the 6th century to talk about Italy, but that name moved around, so it was used of Spain also, as the Greek understanding of the Mediterranean improved.
Williams, Beyond the Rubicon, is a nice study of Cisalpine Gaul that treats the use of the word "Italy" as a geographical and political space over time. The best discussion of the scholarship about the use of the word is probably in the Inventory of Archaic and Classical Greek Poleis under the chapter on Italy.