[psacawa]

If you are asking for examples of brutal acts performed or ordered by Muhammed, here is a long list [0]. Most notable to me is the murder of 600-900 captive non-combatants. This is referred to as the massacre of the Banu Qurayza (woman and children then made slaves).

I suppose you brought up Muhammed on the basis that his venerated status in Islam enables us to significantly extrapolate Muslim culture from his own personal culture. I will therefore state that the evidence of Quran/Hadiths yield evidence of great brutality in the person of Muhammed, which therefore may inspire brutality and violence in any devout followers of his, or in the broader Islamic culture. This is certainly conducive "creating criminal gangs".

[0] https://wikiislam.net/wiki/List_of_Killings_Ordered_or_Suppo...