As Mahayana Buddhism emerged as a separate school in the 4th century BC it emphasized the role of bodhisattvas, compassionate beings who forgo their personal escape to Nirvana in order to assist others. From an early time various bodhisattvas were also subjects of statuary art. Tibetan Buddhism, as an offspring of Mahayana Buddhism, inherited this tradition. But the additional dominating presence of the Vajrayana (or Buddhist tantra) may have had an overriding importance in the artistic culture. A common bodhisattva depicted in Tibetan art is the deity Chenrezig (Avalokitesvara), often portrayed as a thousand-armed saint with an eye in the middle of each hand, representing the all-seeing compassionate one who hears our requests. This deity can also be understood as a Yidam, or 'meditation Buddha' for Vajrayana practice.