The root reason that Afghanistan will always be "the graveyard of empires" is the Durand line established by the British in 1897 to split up Pashtun tribes; the cleaving of "Pashtunistan" leaves some Pashtuns in Afghanistan and the rest in Pakistan.
Historically, Pakistan, has left this area (North and South Waziristan) alone, not pushing their government on them. They have co-existed, sometimes having battles, but these have been resolved in the past. Since the Pakistan Military (and U.S. DRONES) began to fight here, it means that the battles will never end, the Pashtuns will seek revenge forever.
There’s a tale of a 300 year-old feud mentioned in their paper “No Sign until the Burst of Fire, understanding the Pakistan -Afghanistan Frontier”, Thomas Johnson and M. Chris Mason state “According to tradition, members of the Pashtun Hill Tribes are descendents of Karlan, a foundling adopted as the fourth son of Qais Abdur Rashid, a contemporary of the Prophet Mohammed and the Ur-ancestor of the Pashtun ethnic group. The Hill Tribes, or Karlanri, include many of the warlike tribes, such as the afridis, Daurs, Jadrans, Ketrans, Mahuds, Mohmands, and Waziris. Of all the Pashtun tribes, the Qaziris or the greater Waziristan (a region that includes North Waziristan Agency, South Waziristan Agency, and the Bermol District of Afghanistan’s Paktika Province) are reputed to be the most conservative and iracible. The Waziris pride themselves of never having paid taxes to any sovereigh and never having their lands, which they consider veiled, or in purdah, conquered”
The DRONE attacks in North and South Waziristan have killed Pastun Tribal leaders, some are called “Taliban”. The tribes in these areas (over 350 separate tribes, according to Johnson/Mason) have many clans (or Khels), and some are so large there are sub-clans. The Pashtuns have a social code called “Pashtunwali”, which means “the way of the Pashtuns”. This social code has kept the Pashtun Tribes as a unit for over 1,000 years. The Pashtuns follow the code to maintain “Honor”. The Pashtuns settle their differences themselves, by following their codes. They wil accept no law but their own.
These core tenants of the code include self-respect, independence, justice, hospitality, forgiveness, and tolarance. They can not be ruled by a Central Government in Pakistan, that is impossible. Same for the Pastuns on the Afghanistan part of the border.
They go by the same code.
Here’s a map of the Pashtun lands that were divided by the Durand Line in 1893. It just split up 40 Million Pastuns and “made” them Afghaistani or Pakistani.