Well,
1. ISIS doesn't represent Islam and that can be proven from clear Quranic verses as well as practices of Holy Prophet (Peace Be Upon Him) and His companions (May ALLAH be pleased with them). Merely saying yourself a Muslim and raising a black lancer with Kalma Tayyibah written over it doesn't make you a Muslim. Majority of Muslims all over the world condemn their actions and are troubled more than the non-Muslims. Like Al-Qaedah, ISIS is yet another plot to defame, capture (indirect method) and attack (direct method) Muslim countries one by one. So taking ISIS as representative of Islam is either ignorance or a cruelty.
2. Foreign fighters have been invading South Asia for centuries. This part of the world has seen a lot of blood since times unknown. Yes, Muslim (Foreign) fighters have invaded South Asia a number of times but no evidence is present for forceful religious conversion. Spread of Islam can be one of the after effects of these invasions but can't be termed forceful. In fact, these invaders were followed by Muslim Saints like Hazrat Bahaudin Zikria Multani, Hazrat Daata Ganj Bakhsh Ali Hajveri, Khwaja Ghareeb Nawaz, Baba Fareed Ganj Shakar and many others who can be credited for spread of Islam through their preaching and self-less service towards humanity etc.
