As Yaroslav was one of the main persons in charge of the Gu Sect, he had much insider information. In order to live through the ordeal, he chose to cooperate with James and tell him everything he knew. This included the ancient tomb of the Prince of Orchid.
The ancient tomb had been broken into long ago, and the box unearthed from within had long been in Thomas’ hands. It was also a part of his plan to bring the box to Cansington and give it to James.
Meanwhile, the previous Emperor had been