When Chief Seattle says “There is little common between us” in his famous speech of 1854, he means the cultural difference between the Red Indians and the White Americans. That is why their union or a mutual understanding looks very unlikely. Though the White chief sends them message of friendship, Chief Seattle feels that this is not really possible. After all, they are two distinct races with separate origins and separate destinies.
Seattle also explains why they are two separate races, differentiating them on many grounds. This is explained in another answer here: https://englicist.com/questions/two-distinct-races-chief-seattle