Six lower realms

The desire realm (Sanskrit: kāmadhātu) is one of the trailokya or three realms (Sanskrit: dhātu, Tibetan: khams) in Buddhist cosmology into which a being wandering in saṃsāra may be reborn. The other two are the form realm, (Sanskrit rūpadhātu) and the formless realm (S. ārūpadhātu).

Within the desire realm are either five or six domains (Sanskrit: gati, also sometimes translated as "realm"). In Tibetan Buddhism, there are six domains (Wylie: rigs drug gi skye gnas) and in Theravada Buddhism there are only five, because the domain of the asuras is not regarded as separate from that of the nagas. Taoism also features the five realms.

The Śūraṅgama Sūtra in Mahayana Buddhism regarded the 10 kinds of xian as a separate Immortal realm between the deva and human realms.

The thirty-one realms are also known as the "thirty-one paths of rebirth", the "six paths of suffering", the "six planes", and the "six lower realms". They stand in contrast to the higher attainments of the Ten spiritual realms.

Previous actions and thoughts determine which of the six domains a sentient being is reborn into.

The 8th century Buddhist monument Borobudur in Central Java incorporated the trailokya into the architectural design with the plan of mandala that took the form of a stepped stone pyramid crowned with stupas.

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Wikipedia