sorry for the stupid question, I know it's something about "EASTERN", but what Eastern?
Eastern Europe, Middle East?

turkish, arabic and middle east... mainly,
but also some balcanic and east europe styles.

You can load the arabic or other ethnic styles in any western arranger, then often you miss the specific oriental drums, but you can edit the styles.
The most important difference is that you can play arabic scales.
F.i. there's a tone between the F and F# etc...

Roland produces several arranger keyboards customized for specific market/area.
EXR-46OR, for instance (http://www.roland.com/products/en/EXR-46_OR/index.html), is mainly oriented for Middle East market; EXR-E2, instead, is oriented for East Europe market.
They have specific sound sets, styles and features suited for the markets (and users) they are made for.

yes, the exr-e2 was expected with great interest in here (romania) but many were disapointed with the sounds. the styles were appreciated though.