Khorasan between the ninth and thirteenth century AD

One of the important issues in the study of the history of Iranian cities is the study of cities development and its causes in each historical period. One of these periods is the early centuries after the arrival of Islam into Iran, including in the great Khorasan. During this period, although religiously embraced Islam, Iran displayed a different image in the creation of urban culture due to its long history of urbanization. During this period, most of the cities in Khorasan were developed due to the expansion of old cities and major changes in their texture. The expansion of cities was influenced by several factors that affected their expansion in uneven proportions. The most important of these are: Geographical, natural and climatic factor: It includes the issue like existence of water, moderation of region and the good weather, the existence of suitable agricultural land, the proximity to pasture and the possibility of providing wooden products. Security - defense factor: It includes the creation of border cities, the construction of tower and fortification, and enclosing towns by nested fences, the use of natural barriers to protect the cities’ security, strengthening the military capabilities of cities and the use of warfare tools, and rebuilding and consolidating old cities. Economy - trade factor: It includes increased production jobs, the creation of permanent markets in cities, the significance of neighborhoods in the external cities, placing cities on the trade roads and the prosperity of trade with other regions. Governmental and administrative factor: Establishing the centrality of government in a city has always attracted population