There used to be a good all-girl rock band (I mean a band that played its own instruments, not girl singers who hired backing musicians)called "Fanny" (had a medium hit with "Charity Ball" in the late 60s or early 70s) and another called "Birtha" who marketed a heavyish sound under the slogan "Birtha has Balls".

I can't remember if Cheetah was all girl, or just the two singers (who really made the whole sound).

Then there were a few punk girl bands such as Hole, and the Slits.   I think there are still some all female punk bands, and I'm not sure if one is not called "Riott Grrrls".

There are quite a few current amateur female folk duos and trios, and I can't remember the name but I think one is based in Orpington Friday club.

Perhaps it partly depends on what you mean by "band".

It may well also depend on the normal view of assertiveness. In general society still exects more assertiveness of men than of women.