This book is one of the fruits of cooperation, which has become official in the course of nearly fifteen years, between the Institute for Byzantine Research of the National Hellenic Research Foundation (IBE/EIE), and the Institute for Byzantine Studies of the Serbian Academy of Sciences and Arts (SANU). In the past few years, this cooperation has been developed through a joint project, dealing with the last century of Byzantine and Serbian medieval history. However, now, within the scope of this cooperation, a monograph has appeared for the first time, which represents a joint edition of our two institutions. Although the book is the work of a Serbian author and came into being within the frame of the research project - "The Byzantine World in Change (10th - 13th Century)" - of the Institute for Byzantine Studies in Belgrade, it is profoundly connected to the results of some research projects which have been conducted at the Byzantine Institute in Athens. The idea occurred almost spontaneously to produce this joint edition, which could be a symbolical link, connecting the research being done on both sides. The high opinion, which the consulting editors have unanimously expressed about the scientific value of the book written by Bojana Krsmanovic instills the hope that this publishing project will be warmly greeted among the scholars dealing with Byzantine studies. Athens/Belgrade, June 2008 Taxiarches Kolias Ljubomir Maksimovic