Ainu

Ainu is a region in Japan south of Sinnoh, consisting of most parts of the Tōhoku region. Its capital and site of the Pokemon League is Sendai in our age, or Rosewind City in their age.

Ainu is mentioned in Now and Forever in Giovanni's point-of-view. There, the Rocket agents have joined George Hackley's Team Nebula.

Little else is known about this region, though since it is just south of Sinnoh, it has many similar pokemon.