"They were Wens and we were close-minded. It did not matter if they were old people or not," Lan Xichen tells him. "We all believed that anyone associated with Wen Ruohan was no good, it didn't matter what they were."
As for the Burial Mounds, no one paid much attention to that place. Well, they did but due to Wei Wuxian being there. They wanted to get rid of the Yiling Patriarch. Everyone wanted to get rid of the man who stood with the Wens. Even if Jiang Wanyin had told anything it wouldn't have mattered. Not when Wei Wuxian had defected from the Jiang.
"No one wanted to investigate a place the Yiling Patriarch had something to do with."