Complex sentence: Brahmavarta was situated on the confluence of the revered rivers Saraswati and Drishadwati during the Vedic period, where the Rishis composed the Vedas and other Sanskrit Granths, which are the basis of Vedic Sanatana Dharma, presently called Hinduism.
Split into simpler sentences: Brahmavarta was situated on the confluence of the revered rivers Saraswati and Drishadwati during the Vedic period. This was where the Rishis composed the Vedas and other Sanskrit Granths, which are the basis of Vedic Sanatana Dharma, presently called Hinduism.