I do not think one needs to look for evidence of piracy in the Indian
Ocean during the time Mark Twain wrote HF.  I think the use of the
Indian Ocean in the King's story at the Pokeville camp meeting is a
nod and a wink to the notorious pirate Captain Kidd who was associated
with the Indian Ocean and a story with which readers of HF were likely
familiar.  Twain mentions Captain "Kydd" in several other works
indicating he was familiar with the pirate's biography.  He was also
likely familiar with the legend of Kidd's buried gold treasure
somewhere in the Connecticut River.

Barb