The clearest example of a unifying scriptural tradition is the Vedas, composed in Sanskrit from around 2000 to 1000 BCE. Most Hindus revere these as the ultimate sacred literature, which guides their outlook on life.
In ancient times, six major schools of thought in India were known within the Sanskritic tradition. They all upheld the supremacy of the Vedas (as opposed to Jainism and Buddhism, which rejected Vedic authority).