The Vedas (sacred knowledge) are Hinduism's oldest and most sacred texts, composed between 1500 BCE and 600 BCE, and compiled by Vyasa Krishna Dwaipayana. The texts are collections of hymns and ritual instructions used to perform Vedic ceremonies, and the theology and philosophy they contain form the foundation of the indigenous religious systems of India which today we call Hinduism.

The oldest of the four works is the Rig-Veda, a collection of over 1,000 hymns, many of which invoke the deities Indra and Agni, the gods of war and fire, respectively. The remaining books are the Atharva-Veda, a collection of myths, verses, spells, and prayers named after the priest Atharavan; the Yajur-Veda, a book detailing Vedic sacrifice; and the Sama-Veda, a collection of liturgical chants.

Textual commentaries written by priests are attached to and elaborate on each of the Vedas and are also considered part of Vedic literature. These commentaries include the Brahmanas, Aranyakas, and Upanishads.

The Vedas are considered divine revelation or sruti ("that which has been heard") as opposed to texts of human origin, smrti ("that which is remembered"). Brahmin priests methodically memorized the content of the Vedas to ensure their consistent transmission to subsequent generations. The Vedas also provide early records of astronomy and mathematics in India that came out of Vedic ritual and temple construction.

The Buddha is the title given to the founder of Buddhism, and means "enlightened one." He was born Siddharta Gautama, a prince of the Shakya clan whose small kingdom was located on the border between India and Nepal. Although exact dates for key events of his life are still in dispute, most scholars believe he was born sometime in the mid-fifth century CE.

Siddharta grew up in luxury in the palace of his father, Suddhodhana, a warrior-caste king, and in his late teens married the princess Yasodhara. On venturing outside of the palace, he was shocked by the misery he witnessed—of an old man, a sick man, a dying man, and a corpse—and began to contemplate renouncing his princely life.

When Siddharta was about 29 years old, he left his wife and young son to seek religious enlightenment. He spent the next six years in his quest to understand and break free of temporal suffering. He studied under a number of teachers and lived as a wandering, religious ascetic, practicing extreme forms of self-deprivation. He eventually decided to abandon such austere practices and resolved to sit in meditation until gaining enlightenment. One day when he was mediating under a pipal tree in the village of Gaya, later known as Bodhgaya, he reached enlightenment and came to be called the Buddha.

For the next 45 years, the Buddha spent his life preaching his doctrine of the Four Noble Truths throughout northern India and attracted disciples and converts. The Buddha died, achieving parinirvana (final nirvana), at the age of 80 in the town of Kushinagar, in Uttar Pradesh.