The objective of this paper is to present a meta-corpus of diplomatic documents entitled Cartae Europae Medii Aevi or CEMA. It shows the logic and limits of this meta-corpus, which contains 250,000 documents, by specifying both its structure and its possible future extensions. The second part of the paper is devoted to specific examples that will attempt to show the interest of such a database. The third part examine the possibilities opened up by the corpus in terms of historical semantics.