[18] During the formative phase of the empire, the Seljuks first advanced from their original homelands near the Aral Sea into Khorasan and then into the Iranian mainland, where they would become largely based as a Persianate society.

[32] In 1048–1049, the Seljuk Turks, commanded by Ibrahim Yinal, uterine brother of Tughril, made their first incursion into the Byzantine frontier region of Iberia and clashed with a combined Byzantine-Georgian army of 50,000 at the Battle of Kapetrou on 10 September 1048.

The devastation left behind by the Seljuk raid was so fearful that the Byzantine magnate Eustathios Boilas described, in 1051–1052, those lands as "foul and unmanageable... inhabited by snakes, scorpions, and wild beasts."

[32] Alp Arslan, the son of Chaghri Beg, expanded significantly upon Tughril's holdings by adding Armenia and Georgia in 1064 and invading the Byzantine Empire in 1068, from which he annexed almost all of Anatolia.

Malik Shah's brother Tutush defended Seljuk' interests in Syria in the battle of Ain Salm against Suleiman ibn Qutalmish who had started to carve out an independent state in Anatolia.

[38] The Iqta military system and the Nizāmīyyah University at Baghdad were established by Nizām al-Mulk, and the reign of Malikshāh was reckoned the golden age of "Great Seljuk".

[45] It brought chaos to the Empire – a situation later exploited by the victorious Turkmens, whose hordes would overrun Khorasan unopposed, wreaking colossal damage on the province and prestige of Sanjar.

[47] The Tomb of Ahmed Sanjar was destroyed by the Mongols led by Tolui, who sacked the city of Merv in 1221, killing 700,000 people according to contemporary sources during their catastrophic invasion of Khwarazm;[48] however, modern scholarship holds such figures to be exaggerated.

[51] In Persia, Malikshāh's four-year-old son Mahmud I was proclaimed sultan but his reign was contested by his three brothers Berkyaruq in Iraq, Muhammad I in Baghdad, and Ahmad Sanjar in Khorasan.

His nephew, the son of Muhammad I, did not recognize his claim to the throne, and Mahmud II proclaimed himself Sultan and established a capital in Baghdad, until 1131 when he was finally officially deposed by Ahmad Sanjar.

The Dānišmand dynasty founded a state in eastern Anatolia and northern Syria and contested land with the Sultanate of Rum, and Kerbogha exercised independence as the atabeg of Mosul.

[55][56] David IV of Georgia gathered 40,000 Georgian warriors, including 5,000 monaspa guards, 15,000 Kipchaks, 300 Alans and 100 French Crusaders to fight against Ilghazi's vast army.

[citation needed] Ahmad Sanjar fought to contain the revolts by the Kara-Khanids in Transoxiana, Ghurids in Afghanistan and Qarluks in modern Kyrgyzstan, as well as the nomadic invasion of the Kara-Khitais in the east.

[64] Seljuk dominion was established over the ancient Sasanian domains, in Iran and Iraq, and included Anatolia, Syria, as well as parts of Central Asia and modern Afghanistan.

[65] Much of the ideological character of the Seljuk Empire was derived from the earlier Samanid and Ghaznavid kingdoms, which had in turn emerged from the Perso-Islamic imperial system of the Abbasid caliphate.

[83] The Saljuq-nama of Zahir al-Din Nishapuri, which was most likely dedicated to Tughril III, indicates that the Seljuk family now used Persian to communicate, and even were taught about the achievements of their forefathers in that language.

The most significant evidence of the importance of Turkic language is the extensive Turkic–Arabic dictionary, or the Dīwān Lughāt al-Turk, assembled in Baghdad for Caliph al-Muqtadi by Mahmud al-Kashgari.

[99] Through the influence of Tughril's vizier, al-Kunduri, a Hanafi Sunni,[100] the Ash'ari and Ismaili Shi'ites were exiled from Khurasan and cursed at Friday sermons in Seljuk mosques.

[112] In order to counter the ambitions of Abbasid Caliph al-Mustarshid (1118–1135), who wanted to acquire world dominance, in 1124 Mahmūd granted the city of Wasit to Imad al-Din Zengi as an ıqta, and conferred him the Military Governorship of Basra together with Baghdad and the whole of Iraq in 1126.

Turkmens' limitations are adeptly described by Arab scholar Sibt ibn al-Jawzi:[118] The sultan (Tughril I) ordered his soldiers to prepare [themselves] and to send to bring their tents, children and families to Iraq and to head to Syria with him.

This was attested in some earlier buildings, but under the Seljuks it turned into a common characteristic of mosques, madrasas, and caravanserais in Iran and Central Asia, eventually influencing architecture in Syria, Mesopotamia, and Anatolia as well.

[147] Another example of a religious manuscript produced closer to the end of the period of Seljuk Rule is the Qarmathian Qur'an (dispersed folio, Arthur M. Stackler Gallery of Art, District of Columbia, S1986.65a-b).

[129] One example of a secular manuscript is the Nusrat al-fatrah, a historiographical and literary account of the Seljuk period written in 1200 by Imād al-Dīn (Al-Furqan Islamic Heritage Foundation, London).

A relevant occult manuscript from a later period of Seljuk influence in the 13th century is the Dustur al-Munajjimin, otherwise known as the "Rules of Astrologers", while another is the Daqa'iq al-Haqa'iq, or the "Fine Points of Eternal Truths", dating to the Sultanate of Rum in 1272.

[143] The latter text captures an interest in magic and spells, with a particular focus on calling upon spiritual beings, such as angels, through ritualistic acts (Bibliothèque nationale de France, Paris, Persan 174).

[143] For example, while incorporating a Sufi poem, the occult text speaks of supernatural bodies and disputes what Islam considers to be the accepted number of names for God.

[157][158] Starting around the middle of the 12th century, there appears to have been a major increase in the number of artistic metalwork objects produced in the eastern Islamic world (roughly Iran and Central Asia).

[161] The forms produced include both traditional Khorasani types, such as fluted ewers and hooded incense burners, and newe shapes, such as penboxes with rounded ends and candlesticks with drum-like bodies.

[161] The wide range of ornamental motifs include arabesques, geometric designs, real and mythological animals, and even scenes of human figures such as musicians and horsemen.

[161] The general clothing style attributed to the Seljuks is that of the aqbiya turkiyya, or long robe or decorated caftan with “Turkish” cut, with a front opening closing diagonally from right to left.