The drying up of the River Saraswati is a subject of debate and has both historical and mythological dimensions. Saraswati is mentioned in ancient Indian texts, including the Vedas, and is considered a sacred river in Hinduism. However, the timing of its drying up is not definitively established, and it is a matter of interpretation and belief.

Historical Perspective:

1. Pre-Mahabharata Period: Some scholars believe that the Saraswati River began to dry up before the Mahabharata period, which is estimated to have taken place around 3,000 to 5,000 years ago. Geological and archaeological evidence suggests that changes in river courses and climate shifts in the region could have led to the gradual reduction of the Saraswati's flow.

2. Geological Studies: Scientific studies and geological research indicate that the Saraswati River might have been a substantial river system in the distant past. The drying up of the river is attributed to various factors, including tectonic changes, shifts in monsoon patterns, and changes in river courses.

Mythological and Religious Perspective:

1. Mythological Accounts: Hindu mythology contains references to the Saraswati River and its importance as a sacred river. According to some mythological accounts, Saraswati is believed to have flowed underground and merged with other rivers at the confluence of Prayag (modern-day Allahabad). This merging of rivers is considered a significant spiritual event.

2. Religious Significance: Saraswati is revered as the goddess of knowledge, wisdom, and learning. In Hindu religious texts, she is often depicted as a divine river that nourishes the intellect and spirituality of individuals.

3. Mahabharata: In the Mahabharata, there are references to the Saraswati River, which suggest that by the time of the Mahabharata, it might have been reduced to a seasonal or partially flowing river.

In summary, while geological evidence points to the gradual drying up of the Saraswati River over thousands of years due to natural factors, the mythological and religious significance of the river endures in Hinduism. The exact timing of its drying up, whether before or after the Mahabharata, remains a matter of interpretation and belief, and it is a topic of interest among scholars, historians, and devotees.