Seeing a picture of the bag will help date it but we can't authenticate.
If it is genuine leather, it could possibly be by Mario Valentino.
MV had used the brand name "Valentino" long before Garavani Valentino came on the scene. After a court battle with GV, circa 70s, MV retained the right to continue using just "Valentino", but only on bags (shoes?) if I'm not mistaken. That's why you see GVs name spelled out on his bags.
We don't have any label examples of MVs early stuff with just "Valentino" though.