By “area”, it does not just mean geographic alone but also cultural and historical. Take an example from the Philippines. Geographically, you can study the Philippines through the lens of Southeast Asia; historically, you can do that as well. But culturally speaking, you can understand the Philippine society by grouping them with the “Pacific Islanders”, hence the question: “Is the Philippines a part of Asia or Oceania?” and “Is the Philippines a part of Asia or Latin America?”