Italy/Italia was used to designate the peninsula for thousands of years before there was a nation-state called Italy. [0] It was used that way continuously all the way up through the nineteenth century. e.g. Adam Smith, writing in the eighteenth century, referred to "Italy" several times in Wealth of Nations.[1]
[0]: https://en.wikipedia.org/wiki/Italy#Name [1]: https://www.gutenberg.org/cache/epub/3300/pg3300-images.html