The political and administrative unification process under the Roman Empire resulted not only in a progressive linguistic, religious, and cultural homogenisation of the concerned population, but also in the need of trade and exchanges for satisfying new dietary habits and markets. In this paper, we use palaeoecological pollen and macroremain records extracted from Neotoma online database and from scientific literature to analyse the contribution of the Romans in the distribution and cultivation history of Castanea sativa and Juglans regia, two tree species, which are usually considered highly connected with Romanisation. Our results highlight a substantial difference in the impact of the Romans on the history of the two species between the territories of the Western and Eastern Empire, where the Roman influence is much less evident. In the western territories, Juglans regia experienced a significant pre-Roman increase and spread, which was only partially intensified under Roman domination. Castanea sativa, on the contrary, benefited from a significant boost following the Roman conquest, especially in the mountain areas south of the Alps and in France. After the fall of the Roman Empire this led to the traditional medieval chestnut civilisation in which the chestnut tree became a main source of livelihood.