Summary
Shanti-Mantras:
Shanti Mantras are found in Upanishads, where they are invoked in the beginning of some topics of Upanishads. They are supposed to calm the mind of the reciter and environment around him/her. Reciting them is also believed to be removing any obstacles for the task being started.
Upanishad:
The Upanishads are sometimes referred to as Vedanta.The Upanishads are considered to contain revealed truths (Sruti) concerning the nature of ultimate reality (brahman) and describing the character and form of human salvation (moksha).