It is Asian, most likely Chinese. I seriously doubt this is old or jade. The "scratch" style of lines in the design are not a possibility with jade nor is the carving method traditional to Chinese jade work. The ground work and carving method are more common to utilitarian or curio pieces.
A piece of jade that can produce a plate sized carving would be quite valuable, there would be some real effort put into the carving and presentation. Due to it's extreme toughness Jade is a difficult stone to carve. The material this is made of is likely to be Serpentine, Soapstone, Adventurine or possibly Argellite. Other dyed stones are often used to simulate Jade.
Try a hardness test in an inconspicuous spot. If you can scratch it with a knife it's not jade. Suspend the piece gently by it's edge. If you strike it with a piece of metal the stone should ring like a bell if it's Jade. Don't worry about hurting it Jade is one of the toughest material known to man.