This work is devoted to issues of perception by Latin writers of 11th - 12th centuries of such diverse ethno-cultural communities of the Middle Ages, as the Normans and the Seljuk Turks. It turns out that in the view of medieval chroniclers these communities were able to have a common origin. The myth of the Trojan origin was extremely popular in Western Europe over the centuries. In this era the myth of the Trojan origin was not only a relic of the Roman Empire, but actively working as a model of political ideology. Being false in its essence this myth had a significant influence both on relations between peoples and states of Western Europe and on their relations with the Seljuk Turks during the Crusades. It is obvious that the understanding of how Latin authors explain the origin of the Normans and Seljuk Turks will help cast a light upon on the real story of the relationship of these peoples in Asia Minor.