Origin of the word Afghan:
There are different theories about the origin of the word Afghan, its age, and its meaning. Some believe that "Afghan" is formed from "Apagân". The Pashtuns began using the term Afghan as a name for themselves from at least the Islamic period and onwards. According to several scholars, The word Afghan first appears in history in the Hudud-al-Alam in 982 AD.

Meaning and origin of the name "Afghanistan"
The last part of the name, -stān, is an Iranian suffix for "place", prominent in many languages of the region.The term "Afghanistan," meaning the "Land of Afghans," was mentioned by the sixteenth century Mughal Emperor Babur in his memoirs, referring to the territories south of Kabul that were inhabited by Pashtuns .Until the 19th century the name was only used for the traditional lands of the Pashtuns, while the kingdom as a whole was known as the Kingdom of Kabul, as mentioned by the British statesman and historian Mountstuart Elphinstone. Other parts of the country were at certain periods recognized as independent kingdoms, such as the Kingdom of Balkh in the late eighteenth and early nineteenth centuries.

With the expansion and centralization of the country, Afghan authorities adopted and extended the name "Afghanistan" to the entire kingdom, after its English translation, "Afghanland", had already appeared in various treaties between British Raj and Qajarid Persia, referring to the lands that were subject to the Pashtun Barakzai Dynasty of Kabul. "Afghanistan" became the official name when the country was recognized by the world community in 1919, after regaining its full independence from the British, and was confirmed as such in the nation's 1923 constitution.