The main aspects of Tara are the forms which are called the 21 Taras. This teaching
of the 21 Taras appears to have been introduced into Tibet by Atisha. In Nyingmapa,
there are three main lineages of Tara and the 21 Taras. There is a lineage which
is associated with the Khyentse tradition, and there is the Long-Chen Nyin-Thig lineage.
However the most famous lineage of Tara, which is found in all schools, is from
the Terton Chogyur Lingpa. There are a number of small differences between the lineages.
There appear to be two Taras among the 21 which are different between the Atisha lineage and the
other lineages.
Looking at the 21 Taras from perhaps an academic or scholarly standpoint, it seems
that what has been done is to integrate the practice of other female divinities with
Tara. Let me give an example. Most students would, at some point in their religious
life, do a retreat of Tara. Because Tara attainment comes quickest of all, they certainly
would have gained some attainment from that. When they come to practice another
deity, such as Kurukulle, Norgyun or Saraswati, they can connect through Tara. For
example, if they want top do the wealth deity, Norgyun, her mantra is OM BASUDARINI
SOHA. As a form of Tara, it is OM TARE TUTARE TURE BASUDARINI SOHA. In this way,
the attainment gained from doing the main Tara mantra OM TARE TUTARE TURE SOHA in
retreat, is integrated into the evocation of Norgyun, so perhaps one gains that attainment
of Norgyun more easily. Tara gives attainment very quickly and also, she is very
tolerant of mistakes or omissions in the practice, so that one gains those benefits
when doing a combined form.
Combined forms are common in Tibetan buddhism as transitions from one practice to
another. Also, by doing one combined form, one is saved having to do many different
practices. For example, rather than do the practices of Hayagriva and Guru Drakpo
and Garuda and Vajrakilaya, one can do Guru Drak-Pur and combine them all. Or, for another
example, it can be quite difficult to enter into the practice of the Vajra Heruka.
By doing the practice of Yang-Pur (Vajra Heruka and Vajrakilaya combined) one can
create a transitional phase which makes this more possible.
