Bird's-eye View Of Afghanistan

The first part of the name "Afghan" designates the Pashtun people since ancient times, the founders and the largest ethnic group of the country. This name is mentioned in the form of "Abgan" in the 3rd century CE and as "Avagana" in the 6th century CE.
The Encyclopædia Iranica states:
From a more limited, ethnological point of view, "Afghān" is the term by which the Persian-speakers of Afghanistan (and the non-Paštō-speaking ethnic groups generally) designate the Paštūn. The equation of Afghan and Paštūn has been propagated all the more, both in and beyond Afghanistan, because the Paštūn tribal confederation is by far the most important in the country, numerically and politically. The term "Afghān" has probably designated the Paštūn since ancient times. Under the form Avagānā, this ethnic group is first mentioned by the Indian astronomer Varāha Mihira in the beginning of the 6th century CE in his Brihat-samhita.
A people called "Afghans" are mentioned several times in a 10th century geography book, Hudud al-'alam. Al-Biruni referred to them in the 11th century as various tribes living on the western frontier mountains of the Indus River, which would be the Sulaiman Mountains. Ibn Battuta, a famous Moroccan travelling scholar visiting the region in 1333, writes: