Varanasi is also known as Kashi. The city of Kashi has its origin rooted in the time immemorial. It is said to be the oldest city in the world according to our scriptures. These scriptures are 3500 years old and are the part of our sanatana dharma. There is a mention of Kashi in Jabal Upanishad, khand II, Maharshi Atri questioned Maharshi Yagnyavalkya about the realization of true self or atman, in response Maharshi Yagnyavalkya replied, the realization of Paramatman is possible in a place which is free from all the bondages because the nature of Atman itself is free and boundariless. He said that such a place is found between the rivers Varna and nasi. All the indriya doshas or illness of mind and body are cured by the Varna river and indriya papas or sins committed by mind and body are cleansed by the nasi river.
There are illustrations of Kashi in several puranas linga purana, padma purana, brahmavaivarta purana, skanda purana etc. Among them there is an elaborate illustration about Kashi in Skanda purana. Skanda purana is narrated by Lord Skanda also known as Kartik or Murugan, Son of Lord Shiva to Rishi Agastya. In Skanda purana, Kashi Khanda, there are 100 adhyayas, 11000 and more shlokas describing the geography of various temples, story of their construction, introduction to various gods and goddesses of the temples, history of the city and its cultural and traditional system. It is considered to be the directory of those times. In Mahabharata, there is an illustration about few places on earth which are considered to be very sacred, Kashi is one and greatest of all of them.
Kashi is the cultural and spiritual capital of India. There is a story behind its name as mentioned in Vaivaswat manvantar. Vivashwan had a son named Shradhdeva in whose lineage, there was a king named Pururava who married an apsara named Urvasi. She gave birth to a son named Ayur. Ayur had a son called Kshtrabudh and Kshtrabudh had a son called Kashya. Kashya had a son who was known as Kashi. Hence Kashi is named after him.