(dated 682–744 CE). After the discovery and excavation of these monuments and associated stone slabs by Russian archaeologists in the wider area surrounding the Orkhon Valley between 1889 and 1893, it became established that the language on the inscriptions was the Old Turkic language written using the Old Turkic alphabet, which has also been referred to as "Turkic runes" or "runiform" due to a superficial similarity to the Germanic runic alphabets. With the Turkic expansion during Early Middle Ages (c. 6th–11th centuries), peoples speaking Turkic languages spread across Central Asia, covering a vast geographical region stretching from Siberia all the way to Europe and the Mediterranean. The Seljuqs of the Oghuz Turks, in particular, brought their language, Oghuz—the direct ancestor of today's Turkish language—into Anatolia during the 11th century. Also during the 11th century, an early linguist of the Turkic languages, Mahmud al-Kashgari from the Kara-Khanid Khanate, published the first comprehensive Turkic language dictionary and map of the geographical distribution of Turkic speakers in the Dīwān Lughāt al-Turk (). Ottoman Turkish Following the adoption of Islam c. 950 by the Kara-Khanid Khanate and the Seljuq Turks, who are both regarded as the ethnic and cultural ancestors of the Ottomans, the administrative language of these states acquired a large collection of loanwords from Arabic and Persian. Turkish literature during the Ottoman period, particularly Divan poetry, was heavily influenced by Persian, including the adoption of poetic meters and a great quantity of imported words. The literary and official language during the Ottoman Empire period (c. 1299–1922) is termed Ottoman Turkish, which was a mixture of Turkish, Persian, and Arabic that differed considerably and was largely unintelligible to the period's everyday Turkish. The everyday Turkish, known as kaba Türkçe or "vulgar Turkish", spoken by the less-educated lower and also rural members of society, contained a higher percentage of native vocabulary and served as basis for the modern Turkish language. While visiting the region between Adıyaman and Adana, Evliya Çelebi recorded the "Turkman language" and compared it with his own Turkish: {| cellpadding="4" cellspacing="0" width=70% align="center" rules="all" style="margin: 1em; background: #ffffff; border: 2px solid #aaa; font-size: 100%;" |- bgcolor=#DDDDDD | colspan=8 align="center" | Comparison of 17th-century Southern Anatolian Turkman, 17th-century elite, and modern standard Turkish dialects |- bgcolor=#f0f0f0 align="left" ! Turkman language ! Ottoman Turkish ! Modern Turkish ! English ! Turkman language ! Ottoman Turkish ! Modern Turkish ! English |-style="background:#ccc;" |- |