Cleaning a Solid Valance?

We recently have bought a new home. In the living room is a solid valance attached above the front window. It is beautiful -- except for the black dirt along the top of it. I don't know how to take it down, though I do have a few ideas about how to clean it once it is down. The fabric seems to be a heavy, cream, silk type of fabric.

Any tips on how to clean this thing? I am thinking either some type of upholstery cleaner - or even maybe my steam cleaner may help with this.

Thank you,
Dawn in AR