FIRST and tenth Mandalas are the youngest and the longest.The Gayatri mantra is in Rig Veda is taken ffrom Mandala 3.Mandala 9 is completely devoted to Soma.The 10TH mandala contains the Purusha Sukta which explains the 4 Varnas that were born from the Mouth, arms, thighs, and feet of the Brahma or Purusha.Nasadiya Sukta which talks about the origin of the Universe is in the 10th Mandala. Vedas are supposed to be the first religious text of the Hindu religion. Veda means knowledge.There are four Vedas namely,Rig Veda - Oldest and most important Veda, contains the knowledge of chemistry and MEDICAL science.Yajur Veda - Only Veda, which is divided into two parts (i.e. Krishna Yajur Veda and SHUKLA Yajur Veda), contains the knowledge of all sacrificial formula and weapons. Sam Veda - It is the Origin of Indian classical music.Atharva Veda - It contains the knowledge of Ayurveda, also charms and spells hence it is known as BLACK Veda.