Context: Moreover, regional industrial clusters and, more generally, processes of industrial disintegration – most notably the of the Italian industrial districs – are seen as being source of international competitive advantage for firms by balancing competition and cooperation
The use of "the" specifies the districts as perhaps those that you have previously referred to. It depends on what you have written prior to the statement but really it isn't too important and both would be accepted without an English speaker thinking twice about it.