Chief Seattle's speech: real or not?

As I was reading this speech, I found myself torn. Part of me thinks it's hard to make something like this up, and another thinks that it does sound awfully poetic. The person who supposedly translated it doesn't know the language that Seattle's people speak. Some of the things he said were a little strange too. He basically said that they were not worried about losing more of their homeland to the Europeans. I wouldn't think that that would be the case. However, I guess we will never really know whether it happened for real or not.