The fall of the Sasanian is one of the important events of Iran history which led to major developments such as change of religion, culture, political structure, demographic composition and land ownership. Meanwhile, the change in land ownership, which was considered the economic pillar of society and was based on tribute and taxes, was great importance because it affected various aspects of economic and social life of people. Khorasan and Transoxiana, the most important northeastern states of Iran, where most affected by the change in land ownership. So far, however, much research has been done on the consequences of the Arab invasion of Iran, including Khorasan and Transoxiana, but independent research on the causes and factors affecting the change of land ownership in Khorasan and Transoxiana, the method of change and its results has not been done. Therefore, in this research, an attempt has been made to answer the above questions by relying on primary sources and by descriptive-analytical research method. It seems that the type of land ownership before the conquests, how to conquer the land and the motivation of the Arabs to settle in the conquered areas each played a role in how to change land ownership.