Afghanistan’s Pashtun card
Afghanistan could also have instigated Pashtun tribal unrest in an undivided India. From 1893 to 1930 (and to a lesser extent to 1947), Afghanistan provided safe havens and at times weapons to Pashtun guerilla fighters fighting the British in India.

Despite repeated British requests, Afghanistan would refuse to take action against Pashtun tribesmen who entered Afghanistan after attacking British or pro-British elements in India. Afghanistan could have continued to do so, had India not been divided.

In undivided India, like British India, Muslims would have been a minority, and it would have been easier for Afghanistan to incite or encourage violence among the Pashtuns in the name of religion or freedom from unbelievers. After Pakistan’s founding, and given that the Pashtuns either through referendum or tribal jirgas joined the new state, Afghanistan could no longer bank on inciting religious violence.

More importantly and surprisingly, undivided India would have created a big rift between Indian (and later Pakistani) Pashtun nationalist leader Abdul Ghaffar Khan, a close friend of Gandhi’s and Nehru’s who campaigned for a united India, and Afghanistan.

Today, Khan is widely respected in Afghanistan primarily because of his Pashtun nationalist and anti-Pakistan sentiments. However, had India not been divided, he would have been looked down upon in Afghanistan, because he didn’t want a “greater Afghanistan,” which would include all Pashtun majority areas in Pakistan.
To clarify, there is no recorded statement available that Khan wanted Indian Pashtuns to join Afghanistan. Initially, he wanted a united India. When he failed, he wanted autonomy for the Pashtuns of Pakistan.

Today, his grandson and successor Asfandyar Wali Khan has given up those fantasies and is leader of the mainstream Awami National Party in Pakistan, the main opposition party in Khyber Pakhtunkhwa.