But it seems likely... that Sarasvati/Harakhvati was the name for the Helmand. Otherwise it is difficult to understand how Sarasvati could be put between Sindhu and Sarayu as the major intervening river in RV X, 64.9.

Habib argues that the Sarasvati in the Rigveda is the Helmand river. B.B. Lal (2002) commented that Habib "blindly" follows Griffiths misleading translation of the Rigvedic hymn, and that actually the Rigvedic hymn (in the original Sanskrit) "does not put the Sarasvati between the other two rivers". | Lal, B. B. (2002). The Sarasvatī flows on : the continuity of Indian culture. Aryan Books International. 10-11