Sipah-e-Sahaba Pakistan (SSP) and Lashkar-e-Jhangvi (LeJ), both Sunni militant groups, have taken responsibility for the bulk of attacks against Shiite Muslims in Pakistan. Both of the groups are adherents of the Deobandi school of Islam, known for its hardline stance against many common and popular religious practices carried out on the Indian subcontinent.
SSP was established in the early 1980s under the reign and patronage of the second military dictator in Pakistan, Zia ul-Haq. LeJ broke off from SSP in 1996 after its founder, Riaz Basra, had differences with his seniors.