Yuan Shan De told Ye Xiao everything that happened in the past.
According to Yuan Shan De, when the six alive elders completed all the preparations and went out to support their leader, they found that their leader was badly injured. There was not a single part of his body that wasn't wounded and doesn't have dried-up blood.
In short, their leader had already become a bloody man whose figure was distorted enough because of the wounds on his body that the six of them couldn't tell that he is their leader at a first glance.
It took them a while to truly believe. They were all inraged but were helpless as couldn't do anything. Because of the curse of Heavens, they were all weakened greatly and couldn't fight against the huge army of the Ancient Race.