Since the Iranian sources provide no information about the establishment of the Medes Confederation, carrying out a study on this issue is only possible through the non-Iranian sources; although these sources differ, regarding their antiquity, authenticity, the arguments provided, and the fashion of presenting the data. The works of the Greek historians, specifically those of Herodotus and TACITUS have been the focus of attention for long, having been mainly adduced by recent researchers. Despite the contemporary scholars’ tendency to adduce to the works of Herodotus more than any other historian, in order to reconstruct the Medes Confederation, it should be mentioned that the works of Herodotus must be adduced circumspectly. Therefore, the key to the proper understanding of the history of the Medes is the appropriate recognition of the sources, accompanied by a critical view towards them.

Since the the introduction of the arabic word /"anbar/ in the 11th century in European Languages, (fr. ambre; eng. amber from lat. ambra), this word has been used to define two quite different substances: some sort of stone and a perfume. Contemporary lexicographers believe that ancient authors have recognized these two substances as the same and this identification has led to a semantic confusion. These lexicographers, however, have not throughly explained how this terminological confusion has taken place. The source of this confusion has been seemingly justifiable since the mode of extraction of these two natural substances from the sea is the same and so it would be evident that this confusion must have occured. This supposition is not based on medieval documents. The study of the historical documents shows that the designation of these two substances by the same word is problematic. Europeans who have extracted the amber from the Baltic Sea and well knew this substance have naturally assigned local terms to what is known later as amber. On the other hand, the main part of medieval knowlege on amber in the West comes from the oriental sources in Arabic language which the European scholars have exploited and translated in Latin (known as lapidaires in french). In the meanwhile, these main oriental sources have always distinguished the amber ("fossil resin", named kahroba) from the amber as a perfume (named "anbar). So this unexplained confusion apprears somewhere in the West during this period despite the clarity of the classical latin sources (TACITUS, Cassiodorus) as well as the Arabic literature on the subject.