Wrong!!! Alexander wrote that letter to his mother when in Afghanistan, NOT punjab. This fact is agreed upon by every historian. Nice try, but epic failure on your part.
Returning to Afghanistan | Counterfire
The Pashtuns of Afghanistan - Alexander the Great also got in trouble here - NYTimes.com
The Claremont Institute - Alexander in Afghanistan
Alexander spent more time conquering Afghanistan than he did conquering the entire Persian empire (the only military rival of Greece at the time). After Porus, Alexander did not face anymore significant resistance in what is now modern day Punjab. Meanwhile in Afghanistan his troops had to deal with revolt after revolt every other day and ambushes in valleys cost him many troops.
Punjabis only proved to be good mercs, especially for the british
in their wars against and finally suppression of the people of the sub-continent and later in wars against the Central Powers and Axis powers in WW1 and WW2. And thus, for being good mercenary soldiers, the british gave them the title of "martial race".
Though, there is nothing special in the title of "martial race", nor were the punjabies the only ones to have received such a title from their british masters. The Bangalis too were once considered a "martial race" by the britishers, that is until they revolted against the british and thus lost this title for doing so.
Or why didn't the british give the title of "martial race" to the Afghans, the same Afghans who slaughtered a 16,500 strong british army in the mountains of Afghanistan? The same Afghans who defeated britishers in all three Anglo-Afghan wars?
Not a surprise that they gave the title of "martial race" to those whom they easily subjugated, but not to those who handed them their rear ends not once, not twice, but thrice.
'May God deliver us from the venom of the Cobra, teeth of the tiger, and the vengeance of the Afghan'.