The fragments that survived, or were rewritten from memory, are rathered garbled, too, even for religious texts. They are dated to about 1600 BCE. OTOH, the Rgveda is dated roughly to 2000 to 1500 BCE, although it was orally preserved for a long time before being written down. (I should caution that these are the dates arrived at by western linguists; Indian nationalists (Hindutva) have arrived at different numbers.)