The blast in West Bengal's Burdwan district has raised a question in intelligence circles. Is there a joint venture between Bangladeshi and Indian terror outfits? Most experts say the answer is a resounding yes. If the external outfit is the Jamaat-e-Mujahideen Bangladesh (JMB), what are some of the Indian groups linked to it, groups which have helped JMB set up its network and bomb-making units in Bengal?