You may not be able to model this in general with OWL DL but you could model the region controled by P.
:RegionControlledByP a owl:Class;
rdfs:subClassOf [
a owl:Restriction;
owl:onProperty [ owl:inverseOf :isInRegion ];
owl:someValuesFrom :Unit
], [
a owl:Restriction;
owl:onProperty [ owl:inverseOf :isInRegion ];
owl:allValuesFrom [
a owl:Restriction;
owl:onProperty :isOwnedBy;
owl:hasValue :p
]
]; owl:equivalentClass [
a owl:Restriction;
owl:onProperty [ owl:inverseOf :controlsRegion ];
owl:hasValue :p
] .
If the players are all known, you can define such a class for each player. The more general case is maybe expressible in OWL Full but if it is, it involves complicated and non-standard use of the OWL vocabulary, that I'm afraid no reasoners can deal with completely.