About deobandi-bareilwi war, it is recent phenomena. A man named mufti munir shakir was responsible, he first tried to instigate shia-sunni war in kurram. When failed , he shifted to khyber where he successfully instigated deobandi-bareilwi war there and founded lashkar e islam in 2004. Mangal bagh is his successor. Afridis have told me that his origin was unknown, some how he was highly effecient in various dialects and accents of pashto.
I heard he's the worse of the lot. Peshawar's messed up almost exclusively because of Mangal Bagh. Why doesn't army try to eliminate him? I also think he's not too liked by TTP in general, and their alliance is just for convenience.