Hi,
I believe the place to customize country, region and other general objects is same in both ECC and SRM side.
For example, in SRM side, for region maintenance:
SPRO..->
SAP Implementation Guide
General settings
Set Countries
Insert Regions
So if this is already maintained in ECC side, it should also be replicated or transported to SRM side.
I suggest you check if the settings are identical in both sides.
If so, then there is no need to maintain them again in SRM system.
Best regards,
Ivy
