to be a matter of turf

[Sapere_Aude]

What does the bold part mean?

--Today, in big cities, it is likely to be a matter of turf (neighborhood streets) over which rival gangs sometimes fight.

 

[The Newt]

"Turf" means territory; the gangs fight over control of their neighborhoods.

 

[sdgraham]

As an added note, we often refer to such things informally as "turf wars."
Collins Concise English Dictionary © HarperCollins Publishers::

turf war n informal

1. a dispute between criminals or gangs over the right to operate within a particular area
2. any dispute in which one party seeks to obtain increased rights or influence