It looks as though there was an aftermarket radio there before, I've just never seen this wiring configuration...

 

Nope! That's all stock.

For what it's worth: you can simply cut all those off and wire directly into the head unit harness, or have those AND a bulky converter to deal with.

I personally just cut them to save room, but if you plan on putting the stock head unit back in, get the harness.

I try to avoid the stock wiring as much as possible.

 

here is the adapter for the stock wiring.

You plug the stock wiring into this and can connect the other wiring to anything else you want (mostly an aftermarket head unit)

It keeps the wiring "stock" if you ever want to put the stock head unit back in...