The Ashoka Chakra is a depiction of the Buddhist Dharmachakra, represented with 24 spokes. It is so called because it appears on a number of edicts of Ashoka, most prominent among which is the Lion Capital of Sarnath.
According to Hindu religion, Puranas mentioned that only 24 Rishis wielded the whole power of the Gayatri Mantra. These 24 rishis in Himalayas are represented through the 24 letters of the Gayatri Mantra. All the 24 spokes of Dharmachakra are the representation of all these 24 rishis of Himalayas, in which Vishvamitra is first and Yajnavalkya is last who governs the religion (Dharma). Ashoka Chakra is a symbol of Dharmchakra and is also known as Samay Chakra in which all the 24 spokes represents 24 hours of the day and symbolizes the movement of the time.