House Reyne was obliterated after they rebelled against their liege lord, Tytos Lannister, who was perceived as weak by his own vassals. To restore Lannister dominance, Tytos's son, Tywin Lannister, marched against the upstart Lord of Castamere, Lord Roger Reyne, known as the "Red Lion of Castamere". By the end of the rebellion, Castamere had been put to the torch and all members of House Reyne executed. The title is thus a play on words, as the "rains" fall over the empty halls of the "Reynes" who have been killed to the last man, and "not a soul to hear". The lyrics heavily reference the fact that the sigil of House Reyne was also a lion, but a red one instead of the golden lion used as the sigil of House Lannister. The rebellion of the Reynes against the Lannisters was thus seen as a civil war of lions. The song was played by an envoy of Lord Tywin Lannister to truculent House Farman of Faircastle. It was enough to make Lord Farman reconsider his position. http://awoiaf.westeros.org/index.php/The_Rains_of_Castamere