No.
No, there are no other regions in Pokemon Diamond.
There is none
Unfortunantly you cant go to other regions in Pokemon diamond and pearl. its not like leafgreen,firered,gold,silver and crystal version where you travel to different regions. You can't, Sinnoh is the only region available in the game.
Yes there is but its really hard to find.
Sadly no.
The Sinnoh region is the only region in Pokemon Diamond, although the area in the northeast of Sinnoh is like a mini-region.
No you cannot go to other regions in Pokemon Pearl or Diamond version but in Pokemon Heart Gold and Soul Silver you can go to the Jotoh region.
No u can't
What you have to do is catch all the Pokemon from all the other regions(complete national dex.
Pokemon Diamond and Pearl starts in the Sinnoh region and doesn't allow the player to move to other regions. It is considered the fourth generation of Pokemon.
You travel all over Sinnoh and then trade and/or migrate from other Pokemon
There isn't one. You can't travel to other regions in diamond and pearl like you could in the older games. If someone told you there is a code to unlock Cianwood town, don't listen to them.