Used in contexts like personal space, sales regions, animal territories, or areas of responsibility. A straightforward loanword.
営業のテリトリーは関東全域です。
My sales territory covers the entire Kanto region.
Cats try to protect their territory.
That's his territory, so it's better not to go in without asking.
Dogs bark to defend their territory.
We want to avoid entering another company's sales territory.
Invading a neighboring country's territory is a dangerous act.