The first example of pounded sauce at Romans’ time, was the MORETUM, described by Virgilio.
The first recipe of PESTO ALLA GENOVESE (Genoese-style pesto) dates from mid of XIX century, made by Giovanni Battista Ratto, and it’s described in his “La Cuciniera Genovesa” book.
From the excerpts we know that: <we need a clove of garlic, basil or, in case this is not available, marjoram and persil, Dutch cheese and Parmesan, both grated and mixed together, pine nuts, all ingredients pounded in a mortar with a a knob of butter until a paste is obtained. Then we add plenty of oil until the paste becomes a sauce. This sauce is a seasoning for lasagne and gnocchi (trofie), with a little warm unsalted water to make it more liquid>.
However many people say that this recipe is an evolution, or a remake, of another older sauce, that is the “agliata” a garlic sauce made in a mortar, which dates back to XII century and that was used as a preservative for cooked food.
Nowadays, PESTO ALLA GENOVESE is subject to regulations fixed by the Consorzio del Pesto Genovese (Cooperative of the Genoese Pesto),
In big supermarkets (in particular outside Liguria) it is often sold pesto made with vegetable oil instead of the extra virgin olive one, or with walnuts or cashew instead of pine nuts, citric acid, persil for a brighter green colour, and green beans to increase the volume or other ingredients which are palatable but that actually alter the taste of the original pesto.
Pesto is so important for the city, that a world championship of mortar-pounded pesto is held in Genoa every two years as of 2007.