SAP Table
TVBVK Organizational Unit: Sales Groups per Sales Office
SAP table TVBVK has 3 primary key fields being MANDT,VKBUR,VKGRP.
If you are only analysing data from a single SAP instance you may omit field MANDT in your relationships as it will be the same across the entire dataset. On the other hand, if you are combining data from multiple SAP instances you need to take MANDT into account.