The inscription on this sculpture:
"ston pa'i sku 'di gsang phu gling srad (sic) kyi gdan sa pa chos rje shes rab dpal ldan bzang po'i thugs dam du bzhengs."

"this noble sculpture of the teacher was made as the personal image of the Chief Abbot of Sang pu Monastery (gsang phu gling srad kyi gdan sa pa) the Choje Sherab palden zang po (chos rje shes rab dpal ldan bzang po)."

That is what the inscription says, literally.. This sculpture was made for Sherab palden zangpo, the Chief Abbot of the monastery (there were several small monastic residences, he was the head of the whole monastery.) He was still alive in 1476, having ruled already 2 years as chief abbot.

In view of the fact that he had recently assumed the abbot's throne, he had probabl y performed in 1475 the one-year commemoration ceremony of the previous abbot, Sangye Chopa, who had ruled for 14 years until his death. It is a very long reign and he was a great teacher. In my opinion, it is clear that this sculpture represents the teacher Sangye Chos pa and was made to be the personal meditation image of Sherab palden zangpo, to be a reminder of his predecessor and mentor.

The history of the lineage of the abbots of Sangpu monastery is found in Tibetan historic sources, but also in the English translation of one very reliable history book, The Blue Annals. The discussion of Sang pu and the lineage of abbots is page 329 (Roerich 1996, p. 329)