The PEM, a research group located in the Universidade Nova de Lisboa, led by Manuel Pedro Ferreira and cohesived arround  the project "Musical exchanges, 1100-1650: The circulation of early music in Europe and overseas in Iberian and Iberian-related sources" , has compiled over many years a large number of musical sources in both the Portuguese and Iberian archives that are accessible on its webpage. It is a database with just under 20,000 pieces of music, drawn from 250 different sources. It is organized by very different categories that allow researchers to approach the repertoire from the most diverse points of view (chronology, author, notation, genre, place, etc.). Thanks to their efforts, part of this rich musical tradition can be reconstructed and a better understanding of the relations existing between the different Iberian territories, contributing to an indispensable global heritage.