One of  my class is using this book "Tribal roots of Hinduism" By Shiv Kumar Tiwari.
This book support the above research work by Chandra Sunuwar as the book articulates the findings of the tribal practices and the links into vedic-Hinduism.

Here's some excerpt from this book:
The mother -- Goddes or Sakti was worshipped in different manifestation, ie Uma, Parvati, Durga, Kali, Candi or Chandika Devi, Kirata Devi... (Page 91-92)
http://books.google.com/books?id=n0gwfmPFTLgC&dq=Tribal+roots+of+Hinduism&printsec=frontcover&source=bl&ots=keqG0GR_Zy&sig=M84BThdsGsV79KaEb3o_wSzKBtY&hl=en&ei=gUbzSZXgMJuEygWB9fG_DA&sa=X&oi=book_result&ct=result&resnum=1#PPA154,M1

The assimilation to the Kirata god- Siva was not even complete in the age of Patanjali. Because in his commentary on Panini's ... (Page 152-154 )