In the Hindu religious traditions of Shaktism and Shaivism, Kaula, also known as Kula, ("the Kula path") and ("the Kaula tradition"), is a Tantric tradition which is characterised by distinctive rituals and symbolism connected with the worship of Shakti and Shiva. It flourished in ancient India primarily in the 1st millennium CE. Kaula preserves some of the distinctive features of the Kāpālika tradition, from which it is derived. It is subdivided into four subcategories of texts based on the goddesses Kuleśvarī, Kubjikā, Kālī, and Tripurasundarī respectively. The Trika texts are closely related to the Kuleśvarī texts and can be considered as part of the Kulamārga. In later Hatha Yoga, the Kaula visualization of kundalini rising through a system of chakras is overlaid onto the earlier bindu-oriented system. Kaula and kula The translation of the term kula in English is considered difficult and has raised some problems for researchers. The basic meaning is "family", "group" or "self-contained unit". This is explained by Gavin Flood as referring to the retinues of minor goddesses depicted in the schools' literature. Philosophically the term is said to represent a unifying connectedness, beneath the various objects, processes and living entities of this world, which may be identified with these goddesses as aspects of the supreme deity, in some regions the god Shiva, elsewhere a goddess. Another meaning sometimes given to the term kaula is that of a "group of people" engaged together in the practice of spiritual discipline. Kaula practices are based on tantra, closely related to the siddha tradition and Shaktism. Kaula sects are noted for their extreme exponents who recommend the flouting of taboos and social mores as a means of liberation. Such practices were often later toned down to appeal to ordinary householders, as in Kashmiri Shaivism. Fundamental concepts The concepts of purity, sacrifice, freedom, the spiritual master (guru) and the heart are core concepts of the Kaula tradition. Purity and impurity Actions or objects are not seen impure in themselves, rather the attitude is the determinant factor. Spiritual ignorance is the only impurity and knowledge is pure. As long as one is identified with the supreme consciousness, there is nothing impure. The adept is unaffected by any external impurity and makes use of what is reprehensible to attain transcendence. Here arises the antinomian and asocial character of Kaula and the left-handed forms of tantra. Sacrifice Kaula sacrifice (yajna) is defined primarily as