trigger · region

Hands-On Usage

region is commonly used to check whether a state belongs to a specific strategic region, allowing effects in events, decisions, or focuses to apply only to particular geographic areas—for example, triggering occupation policy changes or construction only in Eastern European strategic regions. A typical use case involves the occupation system, where the same logic is applied in bulk to multiple states across a continental bloc.

# In a decision's available block, restrict the decision to only states belonging to strategic region 38 (e.g., the Polish region)
available = {
    FROM = {
        region = 38
    }
}

Synergy

• [is_controlled_by](/wiki/trigger/is_controlled_by): First confirm a state belongs to the target strategic region, then further check whether that state is controlled by a specific nation. Combined, these two narrow the scope of application.
• [has_state_category](/wiki/trigger/has_state_category): Within the same strategic region, differentiate urban tiers (e.g., core provinces vs. rural areas) to avoid triggering effects uniformly on all states.
• [set_occupation_law](/wiki/effect/set_occupation_law): After confirming states exist within a strategic region, bulk-apply occupation laws to states in that region. This is the standard pairing for large-scale occupation management scripts.
• [any_neighbor_state](/wiki/trigger/any_neighbor_state): When iterating through adjacent states, use region to filter and ensure neighboring states remain within the same strategic region before executing subsequent logic.

Common Pitfalls

1. Confusing region with area: region corresponds to the larger "strategic region" in the game's map editor, while area corresponds to the smaller "state area". These two ID systems are completely independent. Using the wrong ID causes conditions to silently fail without error messages, making debugging difficult.
2. Using directly under COUNTRY scope: region is only valid within STATE scope. If called within a nation or character scope without first switching scope via any_state/every_state or similar constructs, the script fails silently. Newcomers often mistakenly assume the ID was entered incorrectly.