The Graustark novels are stories of court intrigue, royal disguise, and romance similar to Anthony Hope's 1894 novel, The Prisoner of Zenda, and its sequels. They were popular best-sellers at the time they were published and the original editions are still readily available in used book shops. The novels gave their name to a fictional genre called Graustarkian: this genre contains tales of romance and intrigue usually featuring titled characters in small, fictional, Central European countries.
During the 1870's, Graustark's ruler, Prince Ganlook, was killed in a war with neighboring Axphain. As part of the ensuing peace treaty, Graustark agreed to pay a large indemnity to Axphain, to be due, with interest, in fifteen years. (Summary from Wikipedia)