The other three Vedas have been composed from the Rigveda itself.
 Rig, Yaju, Sama and Atharva are these four Vedas. 
The Rigveda is poetic, the Yajurveda is prose and the Samveda is lyrical.
The Rigveda is the world's first book and scripture.
 UNESCO dated the Rigveda from 1800 to 1500 BC. 
The Rigveda was probably composed in the Sapta-Sandhav region.

The Mantras or Rithas of the Rig Veda were not composed by a single sage in a certain period, but were composed and compiled by different sages in different periods. In this, information about the political system and history of the Aryans is obtained.

It has a lot to do with geographical location and mantras of invocation of the gods. The Rigveda's verses describe the prayers of the deities, hymns and their position in Devaloka. It also provides information about water therapy, air medicine, solar medicine, manas medicine and treatment by incense etc. In the Rigveda, there is also the story of rejuvenating Chyavanrishi. In the Rigveda, the Yatudhans have been said to obstruct yagyas and cause trouble to the saints.

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RIGVEDA