Ireland, for size

From:
http://indigo.ie/~killeens/celtic.html

:Celtic Ireland was divided into some 150 divisions, called Tuatha,
:(pronounce Too-ah, singular, and Too-aha, plural) each governed by a
:king. The population of ancient, Celtic Ireland is speculated as being
:about half a million, or an average of 3,000 persons per Tuath. Some of
:these kings governed several Tuatha. The local kings paid tribute to a
:regional king or provincial king, who, in turn, often paid tribute to
:the High King.

Half a million, which would match Heortland nicely. And at that time the climate of ireland was warmer than it is now, so the land must have been decently fertile.

Parhaps one could assume that Heortland should be about the size of Ireland.

I'll work on this and see where it would lead me.

        -Adept