The classic Indian epics, such as the Mahabharata and the Ramayana, and the Puranas, refer to diverse kinds of beings, describing them as superhuman or subhuman and other worldly extraterrestrials came to inhabit the living world. Many of these tribes have a strong historical basis, while the supernatural and fantastic aspects are considered literary speculation. These groups include Gandharvas, Yakshas, Kinnaras, Kimpurushas, Rakshasas, Nagas, Suparnas, Vanaras, Vidyadharas, Valakilyas, Pisachas, Rudras, Adityas, Danavas, Maruts, Nivatakavachas, Daityas, Kalakeyas and Vasus.