It's possible, first of all discovered means when word got around and it's not far fetched that before 200 years ago in all that jungley area it didn't get around very fast. Secondly the jungley hills where it's located have low flat land and ocean around it for much easier travel.
Probably when you live in the jungle, weekend camping trips are far less appealing. But then we're relying on a Wiki article that may have been written by someone in the Pentagon who's an expert on Southeast Asia.
