Wikipedia:WikiProject Ecoregions/ecoregionDTD

Standardizing place-names for use in SGML and XML documents is difficult. An ecoregion DTD is the ideal starting point, as unlike national borders, ecoregions don't change much through human history, and when they do, the important characteristics move with them, e.g. their biology and climate. A DTD ties the name of the region to these long term phenomena, while a convention place-name for a town or village ties it to a latitude and longitude. Both rely on the m:spacetime DTD, but beyond that, they fork, the ecoregion is ecology and geography, while a human place name refers to a polity (state) in a language of its inhabitants.

There are over 800 such terrestrial ecoregions on Earth, with names like

Sahara Desert

this drastically expanded after the Roman Empire which exhausted much of North Africa's soil.

Amazon Rainforest

this is drastically shrinking right now.

Despite changes, the fact that there is an ecoregion there has been relatively stable. Border changes can be tracked using other historical data to create moving geographical maps, show population migrations - if and only if references to geography within history are properly standardized.