Good article on the start of the Shia-Sunni violence in the 1980s.
But the article missed on two VERY important factors:
1) killing of Allama Syed Arif ul Hussaini in 1988 by Sipah-e-Sahaba hitmen in Peshawar (as I added in article)
2) Saudi-UAE-Kuwaiti support to Salafi/Deobandi/Wahhabi...