In Sassanian Dynasty, Toos was one of the cities in the route of Gorgan and Nayshabur to Marv, Nessa and finally towards west. After the Nahavand war, a way was paved for passage of Arab soldiers to the east. In the year 29 - 30 AH, Khorassan was conquered by Abdollah bin Aamer and thus the area of Toos came under the jurisdiction of the western Islamic territories. The tower and ramparts (walls) around the city made of brick along with a dome standing 25 m. in height which is called ‘Gonbad-e-Harooniyeh' or the Dome of Harooniyeh, these are counted as the monuments of the ancient city of Toos. In this city several pieces of earthenware, glass, brick and even metal have been discovered, and the evidence of these relate to the Sassanian, Saljuqian, Teimoori and the Qajar periods.