Yes, dreads can be traced as far back as Ancient Egypt. They have dug up mummy's who still have hairstyles such as dreads, cornrows, etc. in tact. Most of the other cultures got their dreads BECAUSE OF the ancient Egyptians. Celts, Indian, etc. all got the dread lock idea from the ancient Egyptians...who were in fact black (though most archeologists love to miraculously argue that they weren't, but that's another story for another day). Throughout the course of history I'm sure we are aware how the ancient Egyptians hairstyle soon made its way to America, and soon got its resurgence again through Bob Marley. Ergo reiterating what I said: dreads are a part of black culture. Always have been and always will be.
I get that it may be different for you since you do not live in America, however considering Marc Jacobs himself is American and he knows alllll about how people react to cultural appropriation, yes it was very wrong of him to include it in his show. His comment just showed the mindset of lots of Americans who at this point in time just choose to not hear and understand all about why CA is wrong. Maybe in Australia you're black and white friendship don't care, but considering this is centered around Americans (MJ being American and all) none of that matters. There are HUNDREDS of people speaking out against the CA he did and the CA problem that we have in America all the time. We are not saying it for no reason. Take something from an ethnic culture, slap it on white skin and all the sudden it's "new" or "edgy" or "trendy"....even though it's been around for decades, just on ethnic skin. It's a form of minimalization. THATS why we speak out.
No, it's not and never will be "just a hairstyle" like people truly want to believe. Saying that, once again, minimizes EVERYTHING, we're trying to say. So does the tired excuse of "but the Vikings did it!" In America black people lose their jobs, get in trouble at school, get told they look like they smell like weed/patchouli (which is why when you said that that did absolutely nothing to help your argument), even get kicked out of the military for wearing all sorts of black hairstyles. But all the sudden when someone with fair skin wears it its high fashion
This happens constantly in black America and peoples lively hoods are on the line for things we've worn for centuries, yet white people can wear it with no problem, I really wouldn't expect you to even understand a morsel of what I'm talking about.
If you still cannot fathom what the hundreds of black Americans are saying and why we are saying either stop the cultural appropriation, or at minimum only use them on your black models, then you need to just read this article.
http://thetab.com/2016/04/05/isnt-ok-white-people-dreadlocks-83996
Hopefully this argument is over.