MC is from earth and gets transported to a martial world (martial artist world), and then he encounters a little white creature and becomes his companion. I remember that creature has the bloodline of an ancestral dragon + another strong one which I can't remember.
I remembered that the MC also goes with geniuses of various places in a dragon island for tempering/trials? ._. and he (I think MC is male) has a white pet which has the bloodline of some strong dragon