Mandukya Upanishad belongs to Atharveda and has been given a very high status. It is the shortest Upanishad and contains only twelve Mantras. Because of its brevity, it becomes difficult for students to understand its entire import without sufficient explanation and therefore Shri Gaudapada Acharya, (Guru of Bhagwaan Shri Shankaracharya) has written karikas (verses written with a view to expound an aspect of the subject matter). 

Brahman is the only reality, nothing else is real. This is the declaration of the Upanishad. The karika explains and proves with various inferences and logic that this universe is nothing but a dream. Challenging our small thinking, Mandukya Upanishad leaves a seeker with intense desire to realise this unwavering Truth.