Pashtuns in the armies of Sultan Shahabuddin Ghori and Prithviraj

According to Gulshan-i-Ibrahimi (written in 1612 AD), Afghans (Pashtuns) and Khaljis formed the vanguard of the army of Sultan Shahabuddin Ghori. The Pashtun and Khalji commanders of the vanguard (مقدمة الجیش), who always boasted of their valour and prowess, fled from the battlefield (along with the right and left wings of the army) in the first battle of Tarain (1191), leaving the Sultan with the centre of Army (لشكر قلب).

Another interesting detail from Gulshan-i-Ibrahimi (or Tarikh-i-Farishta) is that after the defeat in the first battle of Tarain, Sultan Shahabuddin severely punished and humiliated his nobles from Khalj, Ghor and Khorasan who fled the battlefield, but he spared Afghan (Pashtun) Amirs out of prudence. 

In the second battle of Tarain (1192 AD), the 107,000 strong army of Sultan Shahabuddin of Ghor was comprised of Turks, Tajiks and Afghans (Pashtuns).

The 300,000 strong cavalry of Rai Pithora (Prithviraj) in the second battle of Tarain (1192 AD), was comprised of Rajputs and Afghans (Pashtuns).

So Pashtuns were fighting on both sides. For this reason, Sultan Shahabuddin exercised caution in his dealings with his Pashtun amirs. He did not punish and humiliate Afghan (Pashtun) amirs for fleeing from the battlefield in the First battle of Tarain, perhaps fearing that the latter may switch allegiance to Rai Pithora. 

The above snippets are taken from an Urdu translation of Gulshan-i-Ibrahimi (popularly known as Tarikh-i-Farishta). Its author Muḥammad Qasim Hindu Shah was born in Astarabad in northern Persia around 1550 AD. Farishta was his pen name.

Few instances of veneration of trees by Pashtuns in medieval period

The author of Asrar al-Afaghina (completed in 1604 A.D) reports that in late 16th century a tree became a shrine for the Pashtuns of Swat and Peshawar. Thousands of men and women used to visit the tree and made offerings. An officer of Mirza Hakim (the Mughal ruler of Kabulistan) cut the tree to discourage the practice.

The veneration of a tree could be a leftover of the pre-Islamic religion of Pashtuns. According to the "Ajaib al-Makhluqat" of Muhammad al-Tusi (written in 1160-1167 AD), there was a large tree with circumference of seventeen arsh (?) in a Tamarisk forest of the Pashtun country. That particular tree was known as 'the tree of Brahman' (درخت برهمن) and Pashtuns would prostrate before it.

A twelfth-century description of Pashtuns

As late as the mid-12th century, some Pashtuns had not yet converted to Islam. According to the "Ajaib al-Makhluqat" of Muhammad al-Tusi (written in 1160-1167 AD), there was a large tree with circumference of seventeen arsh (?) in a Tamarisk forest of the Pashtun country. That particular tree was known as 'the tree of Brahman' (درخت برهمن) and Pashtuns would prostrate before it.

Following is the original Persian text of the passage from "Ajaib al-Makhluqat" :-

Pashtuns were worshipping a giant tree in mid 12th century ?

As late as the mid-12th century, some Pashtuns might not yet converted to Islam, or they were Muslims but still had retained some of the pre-Islamic practices. According to the "Ajaib al-Makhluqat" of Muhammad al-Tusi (written in 1160-1167 AD), there was a large tree with circumference of seventeen arsh (?) in a Tamarisk forest of the Pashtun country. That particular tree was known as 'the tree of Brahman' (درخت برهمن) and Pashtuns would prostrate before it.