This chapter highlights the violent clashes that mostly happened during Muharram when the Shias perform mourning rituals or azadari in public and take out huge processions. Since the mid-1980s, parties and violent groups, often sponsored by Islamic states, have emerged with a narrow sectarian agenda. The chapter discusses how the level and intensity of violence has tremendously increased in Afganistan and Kashmir due to the availability of weapons and easy access to training facilities. Sunnis and Shias have killed each other in the name of religion in the Punjab, in the North West Frontier Province (NWFP), in Karachi, and in the Northern Areas of Gilgit and Baltistan. This chapter analyzes the internal and external causes of the emergence of the sectarian conflict in Pakistan at the macro level.