(That point have been brought up by GRR Martin himself, who openly praised those books as an inspiration)
The Accursed Kings (Les Rois Maudits) are something eerily similar in concept to GOT, that is ''powerful families and nobles fighting each other for the crown''. With differences, of course.
-It's even more violent than GOT at times
-It happens in real world and, with liberties taken, it's [I]mostly/I] historical. You took that people were willing to do anything for the Iron Throne ? Wait till you see what they are willing to do with the throne of France. That could be labelled, for English readers, as the ''Prequels for the Hundred Years War''.
-The surnatural part is downright inexistant. There is a witch, but her powers mostly boil down to strip naked and have sex with people...(you could argue that this is a lot of the powers of Melisandre previous to Six, but...)
To encourage you to check this serie, the first book open grand style. Two squires are caught having affairs with the daughters in law of King Philip the Fair (Fair as in bishonen). They are sentence to be broken on wheels, then flayed alive, then castrated, then decapitated, then hanged...