The geographical region known for its lush rainforests in Southeast Asia is the Malay Archipelago. This region includes numerous islands such as those in Indonesia, Malaysia, and Papua New Guinea, and is characterized by its rich biodiversity and unique ecosystems. The tropical rainforests are home to an array of wildlife, including endangered species like orangutans and tigers. The area is crucial for global ecological health and is often a focal point for conservation efforts due to threats from deforestation and habitat loss.