Millennia before cacio e pepe became one of the Eternal City’s trendiest pasta dishes and a social media sensation, its starring ingredient graced the tables of Roman emperors. Cacio refers to Pecorino Romano in Roman dialect, and its origins go back to the aged sheep’s milk cheese that was prized by the ancient Romans.

They depended on it as an important source of nourishment for legionnaires—its nutritional value and ability to endure on extended marches made it an ideal food for the soldiers, who were allotted a daily ration of 27 grams. Pecorino Romano today is still made from rich sheep’s milk (pecorino comes from the Italian word for sheep, pecora) and the cheesemaking process closely follows the traditions of the ancient Romans. But most of it is now produced on the island of Sardinia, rather than in the countryside around Rome and Lazio. So why the shift?