There is some discussion about the age of the "Rig Veda." While modern Western scholars tend to date its creation around 1500 B.C.E., other great yogis and scholars date it to before 4000 B.C.E., perhaps as early as 12,000 B.C.E.
Many of the mantras in the "Rig Veda" are hymns to the gods, asking them for help and benefits like health, wealth and long life. Besides hymns of praise, the mantras contain blessings and curses. Originally, the mantras were meant to be chanted as part of religious rituals and this was the main way in which the people communicated with the gods.
The "Rig Veda" is said to be the Veda of mantra. Mantra is the foundation of Vedic yoga, the oldest form of yoga. The "Rig Veda" contains the oldest iterations of many Sanskrit mantras. Many aspects of Vedic science -- like the practice of yoga, meditation, mantra and Ayurveda -- can be found in the "Rig Veda," and many of its teachings are still being used in these practices today.