Enter a valid nationality

What causes this issue?

You have entered nationality key "&V1&". This could not be found in the
table of valid keys (T005).

How to fix this error?

Press F4 to display a list of valid nationality keys and select one of
these.
If you need a new key, please maintain this in table T005 in
Customizing.

Error message extract from SAP system. Copyright SAP SE.