Tus, one of the oldest cities in Iran dating back to the time of 2000 BC, is a settlement located in the Keşfurruz valley between the Kopet mountain range in the north and the Binalud mountains in the south. Its altitude is on average 985 meters. This settlement, located to the west of Mashhad within the borders of Razavi Khorasan Province, in the northeast of Iran, has lost its former popularity today. Tûs it was conquered by Abdullah b. Âmir in 31/651 during the reign of Hz. Osman. Thus, it became one of the Islamic cities. After this incident, Arabs also began to settle in the city, the majority of whom were Iranian. It is known that during the Seljuk period, many Christians lived in the city besides Muslims. According to the geographers of the period, the distance between Tus and Nishabur, one of the big cities of Khorasan, which stands out with its fertile vineyards and gardens thanks to the rivers fed by the mountains in its north, is about 10 fersahs (62.3 km). During the Seljuk period, the city had two big towns called Taberan and Nukan and about a thousand villages. Among these villages, Razkan, Senâbâz and Farmez are the most famous. Tûs is known as an important settlement among medieval cities in that it is the hometown of prominent people of politics, science, literature and mysticism such as the Great Seljuk vizier Nizâmülmülk, Imam-i Ghazali, Firdevsî, Abu Ca’fer Tûsî, Nasîrüddîn Tûsî. The fact that the tombs of Ali b. Musa Rıza The 8th Imam of the Shiites, and Abbasid caliph Harunürreşid are located here has increased the importance of the city. The place where the tomb of Ali b. Moses was located was the vineyard and garden area of Tus at that time and is known as Mashhad, which is the visitor of Iranian Shiites today. Mashhad, formerly known as Nukan, started to migrate with the great massacre (617/1220) committed by the Mongols in Tus, which is located in the area of domination of the Khwarezmshahs, after the plunder and destruction during the Timurid period (1389), with the rapid settlement around the mausoleum of Ali b. Musa Reza, it has become one of the major cities of modern-day Iran. When looking at the sources, the Seljuks first saw Tus by passing through here with the army of Çağrı Bey during the Anatolian campaign. Later, it is understood that the Seljuks were seen again in this city during the Seljuk-Ghaznavid struggle in 1038 and they dominated Tus and its environs, especially Nişabur, from this date on. This place, which was given to Nizamulmulk by Melikshah in 1072 as an ikta, continued to be dominated by the Seljuks until 1153, when Sultan Sencer was captured by the Oghuz. After this date, Müeyyed Ay-aba, one of the emirs of Sencer, mastered Tus together with Nisapur. His dominance continued as an emirate until 1161. After this date, with the death of Sencer’s nephew Sultan Mahmud, Müeyyed Ay-aba had a sermon delivered in his own name and became the king of Nishabur, including Tus. The city was plundered by the Oghuz twice (1153 and 1158) during his emirate’s reign. Müeyyed Ay-aba delivered a sermon on behalf of Arslanşah in 1167 and left the dominance of Tus to the Khwarazmshahs. The existence of the Nizâmiye Madrasa and a madrasah belonging to Gazâlî with 150 students in the city, which was mostly known for its scientific and commercial aspects during the Seljuk period, shows that this place is an important city in terms of scientific activities. It is noteworthy that the city is located on the southern branch of the silk road, contains many trade houses, factories, especially weaving, and sheltered palaces. In addition to these characteristics, agricultural activities have been carried out in the city with its mild climate and wetlands, Tus became a famous settlement with its unique apricots during the Seljuk period. Geographers talk about obsidian stone excavated here and a white stone used for making pottery.