Which Hindu and Buddhist ideas were adopted by theosophists such as Helena Blavatsky?

Helena Blavatsky, a cofounder of the Theosophical Society, integrated several key Hindu and Buddhist concepts into the framework of theosophy.

Central to these adoptions was the notion of reincarnation, which theosophists embraced as a fundamental process of human evolution. By incorporating these Eastern traditions, Blavatsky and her followers sought to promote a deeper understanding of spiritual reality, often interpreting these concepts alongside Western esoteric and occult traditions.123

While theosophy was originally inspired by sources such as Kabbala and gnosticism, Blavatsky’s doctrines took on a distinct Indian character after she moved to India in 1879. The society subsequently became a significant conduit for introducing Eastern thought to the West, encouraging the study of comparative religion and philosophy. Through these efforts, theosophists helped foster public awareness of traditions that emphasize the karmic cycle of birth and death, even if these ideas were often presented in a uniquely idiosyncratic form.431