This is the 14089th most frequent Russian word.
оккупационная
"Occupational" or "relating to occupation (military control)."
In this sentence, 'оккупационная' is used as an adjective to describe an army related to occupation.
Оккупационная армия захватила город.
The occupation army took over the city.
Here, 'оккупационная' modifies 'политика', denoting that the policy is associated with occupation.
Оккупационная политика этой страны вызывает критику.
The occupation policy of this country is subject to criticism.
In this context, 'оккупационная' describes 'историю', linking the history to the theme of occupation.