How to link two tables (they are related in CRM Dynamics but in SQL Server seems to have different IDs)?

Hi,

We hace CRM Dynamics deployed on SQL Server

in SQL Server we can find the table Contact and the table Nationality. Both of them are related in CRM Dynamics but in SQL Server seems to have different ID. The problem is that in the table Contact we have the field new_nationality with an ID like 10000004 however in the table Nationality we have an ID like 6D2C6F1B-7599-E311-93DD-005056846BFB. We need to load both tables and link them in a Datawarehouse, why they have different IDs? How can we link them?

Thanks in advance.