Rgveda from Magadha?

[dean_anderson at SACARI.ORG]

Deshpande says:

-".ZAkalya was only one of the editors of the Rgveda, and that his recension
represents only one of several. We know that ZAkalya based his recension in
part on the earlier recension of MANDUkeya which was prevalent in the
northeastern region of Magadha, while the original Rgvedic hymns were
composed in the northwestern region."

Deshpande, Madhav M. 1995Vedic Aryans, non-Vedic Aryans, and non-Aryans:
Judging the linguistic evidence of the Veda. In George Erdosy (Ed.), The
Indo-Aryans of Ancient South Asia: Language, Material Culture and Ethnicity
(pp. 67-84). New Delhi: Munshiram Manoharlal Publishers Pvt. Ltd.

Why is it thought that there is a Magadha source for ZAkalya?

Dean Anderson