Since ancient times, Khorasan has been the focus of human activities and one of the most important Iranian population centers and prone to social changes. Demographic changes are seen as tangible changes in the history of this region. Due to the geographical location (border region) and more economic facilities than foreign neighbors, this region has played an important role in the process of foreign migration of Iran and the migration of the ethnic groups of neighboring countries to Iran. During the First Pahlavi Period, a large number of Khorasan residents Immigrated to Afghanistan. This article explains the cause of this. The results of the research indicate that, the forced migration of Iranian border residents to Afghanistan and the settlement of a group of Khavari’s peoples, due to the social conditions of the region (ethnic and cultural differences with the Afghan borderline and the refusal of the social reforms of the Iranian government), the geographical and natural conditions of the region (shortage of rain, famine) and the economic difficulties led to the increase in emigration in Khorasan borders. This research has been carried out by studying historical documents, including diplomatic documents of the first Pahlavi period, in the form of library and archives.