Sky Islands

Far in the south of Realm-R exists a set of sky islands housing the Probability Keystone and its guardians. They are an ever-shifting location in the sky above the southern sea. 
 

Changing location

The shifts in location made by the Sky Islands are most commonly known as 'The Probabilities'. Many assume that the Sky Island Guardians directly influence The Probabilities (or make them up as they like), even though no other Guardian creates a set law for a Realm-R location. The Probabilities are a holographic sample space shimmering around the Probability Keystone.
  The Guardians set challenges that use the outcomes in this sample space. Often given as a two-way table or tree diagram, every challenge will ask for a favourable outcome made up of a time when the Sky Islands will move and a length they will move. Once a year a new direction will be calculated. 
 

My Uncle stayed at the Sky Islands for a year and a half a few centuries ago and measured their trajectories. From where they started, they moved after a month, then after two, then after 35 minutes, after seven and a half days and then after 10 months. They have moved 1 m, 12 m, 2 cm, 2 km and then 98 mm. They started out going directly west, but then changed direction to S43(deg)E.

— Akna

And was there a reason he was doing that?

— Government intern

He's my uncle - does he ever have a reason for what he does?

— Akna

 

Inhabitants

There are no big settlements on the Sky Islands, though a few small tribes will spend a few centuries on the Islands once a generation or two. There is also a destination wedding venue with a hot spring. 
  Most creatures on the Sky Islands either have wings (such as the Simugazegle - a monster that looks a little bit like an Earth gazelle with eagle wings) or are so tiny that they will never have need of leaving an island (such as the Dependobugs).
  The Sky Island Guardians also live on the Islands. There are 3 of them, with at least one always around the Probability Keystone, and at least one always checking on the monsters and Islands (travelling between the 5 islands of the Sky Islands).