In Pali Literature the Asuras are classed among the inferior deities together with the supaṇṇas, gandhabbas, yakkhas, garuḍas and nāgas. Rebirth as an Asura is considered as one of the four unhappy rebirths or evil states (apāya), the others being hell, animal, and ghost realms. It.93
The fight between the Devas and the Asuras is mentioned even in the oldest books of the Tipitaka and is described in identical words in several passages. DN.ii.285 SN.i.222 SN.iv.201ff. SN.v.447 MN.i.253 DN.ii.2851 DN.ii.2853
A chief or king of the Asuras is often referred to as Asurinda, several Asuras being credited with the role of leader, most commonly, however, Vepacitti SN.i.222 SN.iv.201ff. and Rāhu. AN.ii.17 AN.ii.53 AN.iii.243 Besides these we find Pahārāda, AN.iv.197 AN.iv.200 Sambara, SN.i.227 Verocana, SN.i.225 Bali, DN.ii.259 Sucitti, DN.ii.269 and Namucī. DN.ii.269
There were evidently several classes of Asuras, and two are mentioned in the Pitakas, the Kālakañjakas and the Dānaveghasas. The Dānaveghasas carried bows in their hands. The Kālakañjakas were of fearsome shape, DN.ii.259 and were considered the lowest among the Asuras. DN.iii.7
A story is told by the Buddha SN.v.446 of a man who once saw a whole army with its four divisions enter a lotus stalk and the man thought he was mad. But the Buddha says that it was an Asura army in flight. Here the Asuras would seem to be fairies or nature spirits.