How can I put a start region when am using world builder ??

[Lava]

<Civilization_Start_Region_Priority>
<Row>
<CivilizationType>CIVILIZATION_CELT</CivilizationType>
<RegionType>REGION_FOREST</RegionType>
</Row>
</Civilization_Start_Region_Priority>

I can't find "REGION_FOREST", how can I put that in world builder ??
Is Asia, Europe, Africa and America a region ??