Rhelasia is a country that, until very recently, was divided into two nations.
Rhelasia was founded in 1855 and it was ruled by the Bokun Dynasty. After World War II, it was divided into North and South Rhelasia by the great powers.
After years of conflict, the leaders of both opposing sides, General Singh Manh Li and Prime Minister Tseng, agreed to bring in an independent arbitrator, Lex Luthor, to settle the dispute and reunite the country. Despite two attacks by Cheshire, both delegates became so impressed with the weapon technology used to create Mercy that they agreed to sign a treaty that could one day lead to reunification.
"Bokun", the dynasty that ruled Rhelasia, means "split" or "cleave" (버근하다) in Korean, which was the ultimate fate of the country. 
Rhelasia was created by Chuck Dixon in the first Birds of Prey one-shot.
It seems to have been based on the real life nations of North and South Korea, with a nearly identical history, relations, and respective political systems.