Apparently, "Aravis" is a name entirely invented by C.S. Lewis. I did find an interesting website which offers a criticism of what the writer perceives as C.S. Lewis' portrayal of the Middle East in his Narnia stories. The writer points out that the names of the Calormenes (the race to which Aravis belongs) all have mock Arabic names, and the Calormenes don't compare favorably with the Narnians (who supposedly symbolize the British, or Western civilization).
The funny thing is (which the writer of this piece doesn't mention) is that Aslan (the Lion/Christ symbol first encountered in Narnia/The West?) means "lion" in Turkish.
http://www.physicsroom.org.nz/log/archive/2arab.htm
-- Nanaea