Persia (Iran) is considered one of the oldest civilisations; because of its especial geographical and geopolitical position, economic conditions and numerous other factors, it has always attracted the attention of rulers and natives of other countries. This has resulted into extensive relations between Persians (Iranians) and other nations throughout history. As a result, along the Persian (Farsi) language which has been used to communicate by different people settled in this territory, as befitting each era, a variety of foreign languages also rose in popularity. Moreover, the issue of teaching and learning foreign languages across this land, especially in recent centuries, has been among the concerns of its inhabitants. Employing historical and linguistic research, this article, which is prepared by scholars of linguistics and history for the very first time in the relevant world literature, aims to discuss the position of foreign languages in Persia (Iran) and the changes in their status in different eras, from the past to the present. The examination of historical and linguistic documents as well as of existing knowledge depicts an impressive picture of the number of languages that were spoken throughout Persian (Iranian) history as well as their diversity.