Sets of links to online material on Nubia and Sudan cannot avoid mentioning academia.edu.
So, one can find today there 256 documents on Sudan and 115 documents on Nubia!
Not bad at all especially considering that these numbers may be increasing as we write these lines!
Just as a small accompaniment to the fourth volume of Nubian Letters:
Medieval Sai Project 
Reblogged this on Sudan Hub Ltd: Est 2011.