Another scenario focusing on Indo-Afghan relations...
IOTL, the Second Anglo-Afghan War (1878-80) was an armed conflict fought in Afghanistan that pitted the British, who intended to estabilish an embassy in Kabul, secure their border, and perhaps also appoint a puppet Emir, against the Barakzai Afghans, at first led by Sher Ali Khan, then by his son Ayub Khan (governor of Herat) after Sher was defeated. The war broke out de jure over a diplomatic dispute, and de facto over the long-running Great Game between the British and Russian spheres of influence in Asia.
At first, the British and their subordinate Indian troops were successful, ousting Sher Ali and installing one of his sons, Muhammad Yaqub Khan, as a puppet ruler. However, the war continued as his sibling, Ayub Khan, took over the torch of the Pashtun resistance. Ayub managed to defeat the British by surprise at the Battle of Maiwand in 1879 (subtly referenced in the Sherlock Holmes series). However, after advancing upon Kandahar and meeting the British in another battle of roughly equal numbers on both sides, he was defeated. Both sides, exhausted by the inconclusive fighting, signed a treaty that demarcated the Durand Line as the border between British India and Afghanistan, later between Pakistan and Afghanistan.
But what if the rebel Barakzai Afghans had managed to defeat the British in Kandahar, in late 1880? From accounts of the situation, despite the British small arms superiority (they had the Martini-Henry), the Barakzai Afghans actually had superiority in quality of artillery as a result of mutineering Afghans coming from the British side who brought some cannons in. This was decisive for Ayub's victory at Maiwand, a year before Kandahar. Could he pull off another victory and rout the British?
How much territory could Ayub's Afghan emirate conquer in the aftermath of such a victory? Balochistan would be a nice addition, as it'd provide the Afghans with some sea access, while the Northwestern Frontier Provinces and Peshawar could be nifty as a new border. Any further thoughts?