he is recognized in portugal and internationally as one of the most distinguished scholars of the history of medieval portugal, and much of his scholarly work is largely devoted to that period. his works include, among others, "ricos homens, infanções e cavaleiros" (on the medieval society), "fragments of a medieval composition" (in response to the arguments of antonio borges coelho), and "identification of a country essay on the origins of portugal (1096–1325)" (vol. i - 'opposition' vol. ii - 'composition'), with five editions constantly revised and updated between 1985 and 1995. mattoso was awarded the alfredo pimenta prize of medieval history, and the non-fiction prize of pen club for this work. he was also awarded the fernando pessoa prize in 1987, among other important distinctions.