Magento

I need to sort products By selecting two options.
As in magento on product listing page(layered navigation) you
can list products based on attributes(as you can select price to show all the products in that price range or
you can select color and list product based on that)

What i need is that i need this kind of listing on two attributes eg region,color

Every product will be having region like Africa,America,Pacific and color like red,green blue
user should be able to see products from africa and having color red.user should be able to have listing based on both selection.

how to achieve this.please help.