Yes but way before any H. Rider Haggard story, the real-life Genghis Khan infamously killed an enemy by pouring a boiling pot of (SILVER) over his head.
Obviously George Martin uses much real life historical figures and events to influence his work.. heck the whole Dothraki are essentially Mongols!
Aegon the Conqueror crossed his Narrow Sea, whilst William the Conqueror crosses the English Channel..
I consider myself somewhat of a historian so I can put up more G.O.T. / history cross-references.