Ghur is a mountainous region watered by the river Harirud which also gives Herat its name. Mainly because the Ghurid Empire lasted barely 50 years, origins of the dynasty which reached its peak during Ghiyasuddin Mohammed and his brother Moizzudin Mohamed bin Sam otherwise known as Shahabuddin Mohammed of Ghur are surrounded in mist.
Ancient Khurasan was vast and the term applied to virtually all the area of Eastern Iran up to the banks of the Amu Darya (River Oxus). Even though Khursan was captured during the late Umayyad period around 750 AD, it was populated largely by Zoroastrians, Buddhists & pagans well into the time of Samanids in the 9th Century.
Historically accepted origin of the word Tajik is Middle Persian tāzīk (‘Arab).’ Hence the pagan Turks of Central Asia adopted a variant of the Iranian word, täžik/ Tajik to designate and all those people who had converted to Islam. Writers of the Ghaznavid, Seljuk and Atābak periods (ca. 1000–1260) adopted the term and extended its use to cover Persians in the rest of Iran, now under Turkish rule as early as end of the 10th century.
Even after 250 of the start of the Abdali Afghan rule, majority in the Ghur province is Farsiwan (Persian speaking). It is therefore doubtful if Ghurids were Pashto speaking. Probably Ghurids, like their adversary Ghaznavids were ethnic Tajiks.
Current fame of the Ghur is due to the brick built Minaret of Jam at Firuzkuh (Turquoise Mountain).