Many of the sillier ideas in this story are my own inventions.  In the less that totally ridiculous concepts (like T'Ang), there was at least an attempt to use canon references as inspiration.

Appendix B of the Return of the King.  The entry for the year 1975 indicates that Arvedui, the last king of Arnor, drowned in the Ice Bay of Forochel.  The ship he was aboard was also carrying two palantiri; one from Amul Sul, the other from Annuminas. Odob, not being the most clever of pinnipeds, takes almost a year to discover the second.

Thorin's map in the Hobbit mentions 'the Withered Heath whence came the Great Worms'. It is mentioned that Smaug was the last of the Fire Drakes.  Tolkien neglects to make any specific mention of the Cold Drakes at this particular time and I've exploited this loophole to create Lithul.  By the Fourth Age, magical creatures like dragons are dying out.  Lithul (roughly translates to Ash Breath) could not be too ferocious.  I used artistic licensce to give him asthma. 

The inspiration for the Hosluin can be found in Book 12 of the History of Middle Earth, The Five Wizards, which states that the two blue wizards went into the East and started a fifth column movement against Sauron by organizing the tribes of men who had revolted against Sauron's rule.  Something obviously went wrong with this particular branch of their sect.   Hosluin loosely translates to Blue Horde.  It should be probably be Luinhoth.  This is what happens when you don't study Sindarin properly.

Somewhere in the middle of writing this story I watched the animated movie The Road to Eldorado.  It occurred to me that this story has a lot of elements in common with the old 'Road' movies featuring Dorothy Lamour, Bing Crosby and Bob Hope.  This was instumental in deciding the location of the final chapters; the shores of the Sea of Rhun.  I was sorely tempted to add a subtitle, 'The Road to Rhun', but was worried people would throw rotten vegetables at me if I did.