The first two Daos were the ones that produced the most Emperors in the universe.
Although Jian Wushuang didn't know much about the Emperors, based on what he had found in some relics, the stronger the Emperor's Dao was, the harder it was to improve it.
Although one's life was infinite, if one's grasp of the Dao remained stagnant, it would affect one's state of mind, causing one to fall into madness and collapse.
Many of those who entered the Great Desolate Wilderness were the same.
Many cultivators comprehended a Dao that belonged to them when they were at the Yan Immortal level. In the beginning, they were still ignorant and could not differentiate the levels of the Dao.
However, some powerful factions would nurture their Princes, Saints, and Dao Children to comprehend some high-grade Great Dao, which was a third-grade Dao.