The aim of the study is the overall exposition of the written sources on the Baltic tribes and their contacts with the neighbours in the 6th – 11th century. Tacitus was the first who mentioned the Baltic tribes in the 1st century A. D. by the name of Aestiorum Gentes. He comprehended the Aestiorum Gentes as the totality of the Baltic tribes. Another important source, distinguishing the Baltic Galien and Sudauen tribes is the writings by Ptolemy (2nd century A. D.). Some important and interesting information on the Baltic tribes can be found in the letter, written by Theodoric the Great, King of the Ostrogoths approximately in 523-526 and presented by Cassiodor. His “History of Goths”, presented by Cassiodor’s contemporary Jordan is important for the Baltic history. Jordan also specified the habitat of the Aestiorum Gentes, i. e. to the East of the Vistula and to the North of the steppe zone. Tacitus presents ethnographic information on the Aestiorum Gentes and Cassiodor’s information is more of a political character. According to Cassiodor, after the downfall of the Roman empire the Aestiorum Gentes were still related to the Goth rulers. It is clear that in the 6th century the Aestiorum Gentes resolved very important issues in Italy therefore some of them understood the language, spoken by the Goths or knew Latin. The authors of the written information on the Baltic tribes of the 6th – 11th centuries were not Balts themselves, the information was received through intermediaries. In addition, the compilers of the chronicles, descriptions or documents were representatives of large countries or tribes therefore their information usually contains data on their intentions to conquer the Baltic tribes and make them pay toll
