These habitats were released in the Ancient World and used only for Ancient World Dragons.
When the Ancient World was first released on mobile, 3 habitats only were available which were Beauty, Magic and Chaos , then after a while Happy and Dream became also available and at last Soul was released.
The time of releasing a habitat is the same as releasing it's dragons : the soul habitat weren't available as there wasn't any soul dragons released yet, but when they were added it became available.