Tradition and purpose of prostration practice In the triratna Buddhist community (who I practice with) there is a prostrations  practice for those going through the ordination process. I'm sure we have taken this practice from another tradition.I'm fairly certain it is Tibetan but can anyone give details of the exact place in the Tibetan practice this comes from and also what is the purpose of this practice. How does it fit into the system of practice and what effects this practice has on the practicioner.
Some texts attribute the original authorization of prostration to the Buddha himself, although they are clear to differentiate between the Hindu Bhakti and guru worship.
http://www.accesstoinsight.org/lib/authors/khantipalo/wheel206.html


  However, He did lay down three forms of reverence for bhikkhus;
  wearing the robe with the right shoulder bared, kneeling down, and
  holding the palms of the hands together in the gesture of reverence.
  Prostration at the feet of the Buddha is also mentioned many times in
  the Suttas. Lay people are free to show their reverence in any
  suitable way and people of those times were recorded in the Suttas as
  expressing their reverence variously:
  
  So the Kalamas of Kesaputta approached the Lord. Having approached
  him, some prostrated towards the Lord and sat down at one side; some
  greeted the Lord politely, and having conversed in a friendly and
  courteous way, sat down to one side; some raising their hands in
  añjali to the Lord sat down to one side, some called out their names
  and those of their clans and sat down to one side; while others saying
  nothing sat down to one side.
  
  — Kalama Sutta, Anguttara-nikaya iii 65 (PTS edition). See A Criterion
  of True Religion, Mahamakut Press, Bangkok, and The Kalama Sutta,
  Wheel No. 8, BPS, Kandy, Sri Lanka.


And additional evidence of the Buddha accepting prostrations
http://en.wikipedia.org/wiki/Prostration_(Buddhism)


  In the Pali canon, laypersons prostrating before the then-living
  Buddha is mentioned in several suttas.[3] In Theravada Buddhism, as
  part of daily practice, one typically prostrates before and after
  chanting and meditation. On these occasions, one does typically
  prostrates three times: once to the Buddha, once to the Dhamma, and
  once to the Sangha. More generally, one can also prostrate before "any
  sacred object of veneration."[4]


But is there evidence of prostrations by religions previous to Buddhism?
http://www.chayas.com/qidah.htm


  Bowing, kneeling, yoshev la'areS, qidah &amp; prostration [to the one G-D]
  originated in authentic Torah Teachings (the Torah of Moses). It
  certainly preceded Islam and Christianity. It is still practiced (to
  some extent) today and is/was retained by a minority of Jews, even
  during the Middle Ages. And while portions of this original practice
  may (or may not have) been copied by other religions, anyone familiar
  with ancient practice knows we still preserve the original method of
  prostration. In my opinion, a popular return to proper Jewish
  prostration or qidah, (which brings about focused, meaningful prayer)
  will result in a greater level of shifa for the Jewish people (and the
  world). This translates into a greater level of Divine protection
  (based on concepts in 'The Guide' / Moreh Nevukhim).


So there may be evidence of your particular Buddhist sect deriving the tradition, but if your question is where was prostration first introduced there is evidence that others preceded Tibetan traditions.