At a recent demonstration in Bonn, violent Islamists injured nearly 30 police officers, with two suffering severe injuries. What is behind Salafism in Germany, and where is it heading?

"Mother, stay strong - I'm waging jihad," sings a young man's voice in German as close-up photographs of dead children with visible shot wounds appear on screen. A Salafist from Bonn, Germany who now lives in Afghanistan put the video online.

It is a propaganda video intended to entice new recruits to come to the Hindu Kush and join the holy war.

In the last two years, Germany's Federal Office for the Protection of the Constitution has noted "increasing travels in the direction of Afghanistan and Pakistan" from people who come from "milieus influenced by the Salafist ideology."

Furthermore, "almost without exception, all of those connected with Germany that have joined up with or supported violent jihadist movements, had prior contact with Salafists."

Salafism is not a unified movement. Instead, it is an umbrella concept for a number of branches of Sunni Islam.

"They propagate what they consider an original form of Islam, tracing it back to a 'Golden Age' around 1,400 years ago, from which Muslims have gradually moved away in the course of the centuries," said Raul Ceylan, an Islamic Studies professor in Osnabrück.

Their goal is to recreate this original form of Islam, Ceylan explained, and they reject all forms of subsequent religious or social "developments." Just a few radical groups within the movement advocate violent conflict, though.

What is it that makes such extremist groups attractive to recruits?

"For one thing, it's the very close and sect-like communal life," said Ceylan. "The more you enter this circle and integrate into its structures, the less contact with the outside world you'll have."

"It's also the attractiveness of simplicity," Ceylan added, referring to the black and white picture that prevails among extremist groups of all non-Muslims being condemned to hell, while all believers will find paradise.

Finally, Ceylan said, Salafist preachers give their followers a sense of being "the chosen ones."

In the last few months, the Salafists have moved beyond basic propaganda. Last year, an association calling itself "Invitation to Paradise” tried to settle in the western German city of Mönchengladbach. Months of protests by residents ultimately prevented that, and the group was forced to disband.