Ismaili spiritual leader
The Aga Khan, spiritual leader of Ismaili Muslims, looks on during a speaking event at Massey Hall in Toronto, February 28, 2014.Reuters

The Ismaili minority in Pakistan, which is known to be a peaceful and progressive community of Shia Muslims, has once again come into focus after a terror attack in Karachi on Wednesday left more than 40 of its members dead. 

Who are the Ismailis?

The 15-million strong Ismaili community is one of the larger sects within the Shia community, and considers Prince Karim Aga Khan to be their spiritual leader.

Prince Karim is a Harvard graduate who took over as the 49th spiruitual leader of the community at the age of 20 in 1957.  He was was born in Switzerland but is a British citizen.

Aga Khan is a title used to refer to the Imam of Shia Ismailis.

The current leader, whose net worth is estimated to be about $800 million, is known not to lead the life of a conventional spiritual leader, but is hailed for his Aga Khan Development Network that has funded charity and development work across the world. 

The Ismailis, who are known to be apolitical, have fallen victims of increasing terror attacks in Pakistan, mainly by Sunni militant groups that view them as heretics.

The Aga Khan condemned the Karachi attack as a 'senseless act of violence'. 

This attack represents a senseless act of violence against a peaceful community. My thoughts and prayers are with the families of those killed and wounded in the attack," the community's spiritual leader said in a press statement. 

Wednesday's attack on Ismaili passengers in a bus comes just months after a suicide bomb attack at a Shia mosque in Pakistan's Shikarpur district in January had killed more than 60 people. 

In 2013, the Tehreek-e-Taliban, the Pakistani wing of the Taliban, claimed the attack on an Ismaili worship place in Karachi that left four dead. 

Why they are attacked?- 

The Sunnis, who form a 85% of the Muslim population in the world, differ from the Shia belief that Hazrat Ali, the Prophet's cousin and son-in-law, was his successor, and instead consider Abu Bakr, a close companion of the Prophet, to be the true successor. 

This divergence in beliefs has been the source of the historical division between the Sunnis and Shias, with groups within the communities often engaging in violence to uphold their beliefs. 

Ismailis, like other Shia Muslims, have often fallen victim to such violence, especially in Sunni-dominated countries such as Pakistan. 

The Ismailis are also seen as a more educated and well-off community among Muslims, which may be another reason why its members are targeted.

More than 1,000 Shias have been killed in the country in the last two years, Dawn reported.

Terror groups such as the Taliban, Al Qaeda and other groups are known to target Shia sects. 

The Karachi bus attack has been claimed by a Taliban splinter group called Jundullah, which pledged allegiance to the Islamic State last year. 

Last year, the Pakistani Taliban had announced an 'armed struggle' against Ismaili Muslims in the Chitral Valley, where a large number of the community used to live. 

"The Aga Khan Foundation is running 16 schools and 16 colleges and hostels where young men and women are given free education and brainwashed to keep them away from Islam," the Taliban had said in a video.