What is the best way to connect a dimension missing in a table ?
Requirement is sum of Orders from Table2 must reflect by Region in Table1.
So how would you know which rows of Table2 belong to which region? To resolve this, you will have to create a table that associates Countries to Regions.
If you have not got the region vs. country look up data then you could probably download something from the web. A quick search found this https://docs.adjust.com/en/countries-by-region/
Obviously it depends on the exact formats you have for Country and Region in your data.