The general approach of Islam was to soften the population with soft jihad and then later wit hard jihad. That is first the come in and up until 1.5% of the population they are exemplary citizens, kind considerate, honest. Then at 1.5% then send in their children to do damage but they say then that that have no control over their children and after all "Boys will be boys." Then at a higher percent the real jihad starts, with murder and terror until the population succumbs and accepts Sharia. This was the tried and true method thorough out the East up until India, and in Europe as in Albania.