Orathos

The fallen island nation the campaign is about reclaiming. Forty years ago (1360s),
a handful of villains and their minions sowed discord until Orathos fell; its people
fled to Varia as refugees. In 1395 the reclamation pact was signed between the
Orathi Militia, Varia, the Firebrands, and the Mage's Society
(see The Coalition), and a foothold was established. The party sails to its shores
in 1396.

Four provinces:

Transcripts frequently render the name "Arathos" — canonically Orathos.
See World History for the timeline of its fall.