The importance of diplomatic exchanges between the Byzantine Empire and the neighbouring states for a better knowledge of Balkan history has been frequently shown by scholars. In this case we study the embassy sent by Andronic II at Skopje at the court of Stephen Uroš III Dečanski. About it we have the account of Nicephore Gregoras. The cause and the intentions involved are explained in this text. On the same occasion, the Byzantine historian provides an eloquent description of the aspect and way of living of the local populations he met during his journey. Among them, a careful analysis recognizes the Vlachs.