It is a Muslim invasion strategy introduced by Muhammad himself, when Muhammad and his good friend Abu Bahkr fled for their lives to Medina from Mecca.
Muhammed switched from just using his mouth to convert followeers as he did in Mecca, to also using the sword in Medina, and it has been that way ever since.
Move in mass into a Kafir area and when the time is right draw the sword. - Tom
Nobody believed Muhammad in the beginning.....even his own family thought he was nuts..he was in fact. All he created in his world was copied and borrowed to devise his agenda. Nothing original. Then he just built this elaborate story about himself and sold it to a back word uneducated peoples....who of course were well familiar with violence.