In the 11th century, the Seljuk Turks emerged as a dominant force in the Islamic world, extending their domains from the delta of the Amu Darya into Iran, Iraq, the Caucasus, Syria, and Asia Minor. Their ascent began in 1040 when they crossed the Oxus River and defeated Masud, the Sultan of Ghazni, at the Battle of Dandanaqan. This victory led to the establishment of the Seljuk Empire under Toghrul Beg, grandson of the confederation's namesake, Seljuk. Toghrul made Nishapur his capital, while his brother Daud secured key cities like Merv and Herat.
The Seljuk Empire reached its height under Alp Arslan, Toghrul’s nephew, whose victories, including the decisive Battle of Manzikert in 1071, expanded Seljuk influence into Anatolia. Alp Arslan was buried in Merv, a city that symbolized the Seljuk era’s cultural and political zenith. Merv became a vital economic and cultural hub on the Silk Road, renowned for its agriculture and role in the movement of goods and ideas. This period also saw Turkmen tribes, who formed the backbone of Seljuk military forces, migrate and settle across Seljuk territories, including present-day Turkmenistan. Turkmen settlement transformed previously uninhabited desert regions into thriving communities, particularly along the Caspian Sea, Kopetdag Mountains, and rivers like the Amu Darya and Murgap.
By the late 11th century, Seljuk control began to fragment. Sultan Sanjar, the last powerful Seljuk ruler, witnessed this decline firsthand. He presided over a turbulent era when the empire faced mounting internal and external pressures. During his reign, Merv was overrun by Ghuzz tribes, marking the beginning of the Seljuk Empire's dissolution. The Ghuzz and other nomadic groups infiltrated settled areas, contributing to the Turkification of regions north of the Kopetdag Mountains. Over time, these Oghuz tribes intermingled with local populations, becoming known as the Turkmen.
The Seljuk Empire ultimately disintegrated in the latter half of the 12th century. With the empire's collapse, Turkmen tribes in present-day Turkmenistan transitioned into independent tribal federations, maintaining their nomadic traditions while influencing the sociopolitical landscape of the region. This period laid the groundwork for the Turkmen identity that would endure through successive centuries.