Its impossible to subdue a society little removed from the 7th century, unless you're willing to replicate the actions of Alexander the Great, Mohammed, Genghis Khan, Tamerlane, Abdur Rahman Khan:
That is, slaughter or enslave all males from any tribes who oppose you [1], take their women for your own [2], and enforce your own culture, language and religion [3].
All of that is rather politically incorrect these days, so Afghanistan and nations like it will remain unconquerable except for nations like China who are still willing to carry out that level of annexation and assimilation.
That is, slaughter or enslave all males from any tribes who oppose you [1], take their women for your own [2], and enforce your own culture, language and religion [3].
[1] https://en.wikipedia.org/wiki/Banu_Qurayza
[2] https://en.wikipedia.org/wiki/Susa_weddings
[3] https://en.wikipedia.org/wiki/Nuristan_Province
All of that is rather politically incorrect these days, so Afghanistan and nations like it will remain unconquerable except for nations like China who are still willing to carry out that level of annexation and assimilation.