In Vajrayana Buddhism, the Womb Realm (Skt. garbhakosa-dhatu, Jp. 胎蔵界 taizōkai) is the metaphysical space inhabited by the Five Wisdom Kings. The Womb Realm is based on the Mahavairocana Sutra.
The Womb Realm is a very popular subject for mandalas, and along with the Diamond Realm (vajradhatu) Mandala forms the Mandala of the Two Realms.