Emma Campbell has an excellent review essay on that subject in the Journal of Romance Studies 4:3 (2004). She looks closely at six recent monographs or collections of essays which attempt to stretch the geographical boundaries of the western Middle Ages, paying special attention to gender studies and postcolonial theory.
I had a difficult time tracking down the volume, but am happy I did. I now have a .pdf version. If you'd like a copy, let me know [jeffreyjeromecohen [at] gmail [dot] com]