This is strictly an out-of-character discussion to establish the history of Hainan. Folks are then welcome to twist this history to their own advantage in other, in-character threads.
Bernhard has indicated to Mac that Iberia gained Hainan in the 1700s, maintained it - loosely, perhaps - until the 1880s, then took a more direct role in governing it. Like other Iberian overseas colonies, it would was merged into the Iberian Federation in the early 1920s.
How and why this happened is the question. I'll propose one explanation here:
-Hainan is a Chinese possession prior to the 1700s.
-In the first half of the 1700s, Spanish missionaries and traders start to arrive from the Philippines. Soldiers arrive later to protect Spanish interests.
-The Seven Year's War (1756-63) sees Britain occupy the Spanish trading posts, just as Britain occupied the Philippines. The Peace of Paris restores both possession to Spain in 1763 and signifies official recognition by the major European powers of Hainan as a Spanish, rather than Chinese possession.
-China has enough problems with foreign powers that it is unable to dislodge the Spanish.
-As part of New Spain, the island is ruled from Mexico until that nation's independence in 1821.
-Mexico's independence forces Iberia (recently created from Spain and Portugal) to shift its administration of New Spain; for the Pacific, this function is shifted to Manila.
-Opening of the Suez Canal in around 1869 brings more communication with Spain, and more interest amongst educated Filipinos in Filipino independence. These folks envision an independent Philippines including Hainan and such main-land Iberian possessions as Macau.
-Most people in Hainan aren't enthused at this; after a century or more of Spanish rule (including conversion to catholicsm), they don't really identify with mainland China, which looks pretty dysfunctional at the moment. Pushing for their own independence looks like it may just set them up as a battleground for other European nations looking to muscle their way in (as is happening elsewhere in Asia). The Hainanese are generally satisfied to stick with the devil they know, Iberia, despite Iberia's less than ideal rule.
-The Iberian-American War, and the historical revolutions in the Philippines and Cuba, leave Iberia with a depleted empire in ~1899. Iberia recognizes that a more mutually beneficial relationship with its remaining colonies will be required, or it will lose them too. Iberia begins a program to establish the colonies (also including Liberia, Ecuador, Central America) as provinces, rather than territories.
-This plan reaches fruition in 1921 with the Federation of Iberia.
-End result: China can claim that Iberia stole Hainan from them - but the majority of Hainese are likely content to remain as part of the Iberian federation and identify more as "Iberian" than "Chinese"...
Thoughts?