Provinces and cities can be renamed if you control the province garrison;
I'm not sure how far up the chain of command that goes. The same applies
to any sublocation in the province; groves, graveyards, poppy fields, etc.
In your example, you would have your faction issue 'name aa00 "Plain of
Death"'.
All you can change is the name (first entry on the line); terrain/feature
type,
continent, and civ level are applied automatically and can't be changed
that way.
I haven't tried to rename garrisons.
-- Carl Burke cburke@mitre.org