Afghanistan counts its Independence from 1919 because before this year, British puppets Amir habibullah and Amir Abdul Rehman were ruling the country who had sold their foreign affairs to British. King Amanullah chickened out after his house was bombarded in third Anglo-Afghan war (which was waged to liberate pashtun areas under British). An iron-willed ruler would have declared Durand line treaty of 1893 null and void after the war. But Amanullah renewed it and signed it again in exchange for so called independence. This was a defeat and sealed the fate of British occupied Pashtun territories with British India. The fact is , the passion of Amanullah for re-unification was short-lived, after disastrous war he learned some harsh realities. He was the one who encouraged hijrat movement to annoy British, but gave up on it after war.
Afghans need to focus on what is left of their country, days of Durrani empire are over long since.
I have gone through the Durand Agreement and it carries the full weight of law and fact. Anybody who signs anything can try to get out of it later on spurious grounds. That way no agreement can be 100% secure if one party later on decides backtrack. The reality is the agreement was signed and affirmed at another point down the road. It is clear. It is unambigous. If Afghanistan goes to ICJ the case would be thrown at the first hearing. Which is why Afghanistan has not taken it to ICJ.
Now the legality out of way let me address the practicalites of the situation. There are nearly 30 million Pashtun's in Pakistan. My opinion is the figure could be higher because of high mobility and non registration. Karachi alone might have 7 million which is same as London. Khyber Pakhtunkwa is far more developed than Afghanistan and will remain a Pashtun province. I think in another 50 years the Pashtun population will increase lot more. Punjab population has began to slow down because of relative prosperity. As that happens the ratio of Pashtun's will increase and go back to the way it was in 1880s because it was the British who with their mass scale irrrigation and people importation from East Punjab increased the population. Given this the future of Pak Pashtun is far from Red Indians.
In 2015 it is time to forget about the past and move forward. If NWFP had joined Afghanistan in 1947 you realize what would have happened in 1979? We would have Red Army bombing Attock and Abbotabad. There would be Red Army soldiers running amok in Peshawar.
Any for me the tragedy is more Pashtun areas like Khost, Gardez etc were not incorporated by the British into NWFP. That way those Pashtuns today would have had some peace at least and not be migrants n Pakistan being treated horribly. On top of that the Pashtun influence on Pakistan would have been even freater. Even now do you think Pakistan can afford to annoy Khyber Pakhtunkwa. I don't think so.
Never mind that even today you know Pakistan made mistakes in Afghanistan but you know even without there would have trouble. The biggest problem in our part of the world is how differant ethnic groups work togather to in peace to build modern prosperous societies. The problem is our people identify with family or tribe and will fight and have war. You can see the result. Do you think Tajik, Uzbek, Hazara, Pashtun are going to be able to find common ground? I doubt it. One wrong move and they will start fighting. Even if they don't fight they barely will put up with each other.
Now compare Europe. English, Germans, French, Italians, Spanish, Danes, Poles, Slovaks, Irish, Norwegians, Swedes, Belgians, Portugese all work togather and look what they have built. Us lot can't even think above tribal level. Have you seen the NATO force in Afghanistan? All Europeans united.
Now today the best thing is Khyber Pakhtunkwa works hard within the federation to build a prosperous law abiding society where children grew up going to school, fed and happy.
And Afghanistan the trouble is NOT going to end. Have you ever checked to see what the Afghan National Army is made up off? Almost the entire officer cadre is Tajik/Norther Allliance. The few token Pashtun they have are just soldiers even then it is a tiny number. This is fact. In fact when ANA moves into southern provinces it is almost regarded as foreign army. I am doing some research on this. If you get time see if you can compare the Pashtun percentage in ANA and then Pak Army and see what is relative balance is.