Especially for Morning Star Tier Beast Masters, who have undergone the Ascension Ceremony at the Mother River and received blessings, their Beast Master Space has become alive, granting it the ability to accommodate more life forms.
The Beast King system transformation also begins from the Morning Star tier. The Beast Master Space can accommodate a large number of Slave Beasts, and at higher ranks, support the propagation of organisms within it.
Therefore, many Beast Masters will strip it off before death, even if they have only a few of insufficient power, they can choose to merge with a small dimension and turn it into a Heritage Relic, to select an appropriate heir for themselves.
However, without the Beast Masters providing spiritual power, most of the Relic Secret Realms will wither away in the Void, and some will begin to merge with the Main World over the long timespan.