I have some data like this below
I would like to make a dashboard that will show you all the related empires based on what you choose (those that existed at the same time AND those in one of it's regions of influence). For example if I choose Rome then it will only show Egypt, Greek and Gaul and not show Byzantine because it is from a later time and not show China because it is in a different region. See below
The simple way to achieve this task is to "Self-Join" I would self-join the data again with Inner join on Region and Era
then, to handle the duplicate rows I would create a calculation
[Empire_Data1] = [Empires_Data2]
and put as false in the filter shelf. then if you drag both Empires field you will the output you are looking for,
Since this is like 20 rows of data, you can perform a self join without any challenge. But you have a lot of rows as in hundreds of thousands or more then, you might want to prep your data before connecting to the tableau.
