It was call Punk at first and not Punk Rock as classic Punk was called. In the ealy 80's it was called Hardcore Punk
Hardcore Punk started in L.A with the band Black Flag and in D.C with the band Minor Threat and Bad Brains; which are the big three bands of early Hardcore Punk.
In the 90's heavy metal bands tried to get into Hardcore with out being Punk. Which is not Hardcore at all. The Hardcore movent and sound is still Punk and always will be. Metalcore is metal music not Hardcore Punk. There is still Harcore Punk bands around today, and that are not metal bands claiming to be Hardcore with out being Punk. A few of them are,
Lower Class Brats
No Use For A Name