Were you looking for the faction specific scenarios of the same name, Isle of the Thunder King or Isle of the Thunder King?
The Isle of Thunder (also known as The Isle of the Thunder King) is a new questing hub zone and scenario location. A recent map of Pandaria shows it north of Townlong Steppes as almost an extension of its archipelago.
Trolls and Mogu have taken up residence here, and seem to be allied with one another. The Zandalari have resurrected the ancient Mogu Thunder King. Whatever their plans, it cannot be good for the rest of the world, if the first Mogu Emperor were to rise to power again.
Jaina Proudmoore and Lor'themar Theron have shown up on this isle seeking to end the threat of the Thunder king. Lor'themar has two reasons to be there. Firstly because justice demands it. Secondly because his people are in need of something powerful they can use in case of an uprising against Garrosh Hellscream.