Age of Rig Veda

One Mr. M.P.Gandhi from Calcutta writes this in his book

 THE Indian Cotton Textile Industry

ITS PAST, PRESENT AND FUTURE

"As is well known, the

age of the Rig Veda itself is not a fully solved problem various ages

being assigned to it from 4000 B.C. to as late as 1200 B.C.,’’

Please share your view about the age of Rig Veda.