Na wrora, you are mistakened.
There are stereotypes and generalizations about Pashtuns being the only ones defending Afghanistan, true that (And, part of it has to do with Pashtuns being the Majority, greater in number) . But, that doesn't mean Taijks haven't fought against the invading forces. I'm talking about resistance against the soviets in Ghazni, Herat, Kabul, Logar, Mazar and the list goes on. You are true up to most extent, Pashtun rebellion always outnumber the Tajik/Uzbek/Turkmen rebellion when it came to invading forces , but that doesn't mean everything was black and white (i.e. Pashtuns (Mujahideen) Vs (communists) Tajiks/and other minority) there were thousands of Pashtuns that sided with the invaders (soviets/British), like the current situations. And, the same goes with the resistance, there are a small number of Tajik and even Hazara resistance going on in Afghanistan