It wasn't difficult for Lin Yuan to ascertain this. All he needed to do was ask the Holy Spirit experts he had taken control of.
Alternatively, he could get the answer by asking Spring and Winter.
Many of the Holy Spirit experts under Lin Yuan came from large species. They did not lack resources during their growth. If there was any chance that they were able to nurture more holy spirits in their divine kingdom, they definitely would not pass up on the opportunity. Hence, it was highly likely that his divine kingdom was special.
Lin Yuan had proven this when he gained a holy spirit in his divine kingdom back when he was only a pinnacle spirit fire expert.
After Lin Yuan used Truth to take control of the holy spirits in Liu Yao and Liu Chen's divine kingdoms, Winter released Liu Yao and Liu Chen from their restraints.
