The Buddhist asuras are derived from the asuras of Hinduism, but have acquired a few distinctive myths which are only found in Buddhist texts.
Buddhaghosa explains that their name derives from the myth of their defeat at the hands of the god Śakra. According to the story, the asura were dispossessed of their state in Trāyastriṃśa because they became drunk and were thrown down Mount Sumeru. After this incident, they vowed never to drink sura again.
While all the gods of the Kāmadhātu are subject to passions to some degree, the asuras above all are addicted to them, especially wrath, pride, envy, insincerity, falseness, boasting, and bellicosity.
Always desiring to be superior to others, having no patience for inferiors and belittling strangers; like a hawk, flying high above and looking down on others, and yet outwardly displaying justice, worship, wisdom, and faith — this is raising up the lowest order of good and walking the way of the Asuras.
The asuras are said to experience a much more pleasurable life than humans, but they are plagued by envy for the devas, whom they can see just as animals perceive humans. The asuras of some inferior realms however, are malevolent (such as the corruptor Mara) and can be referred to as demons. They are alternatively called rakshasas.
They are sometimes referred to as pūrvadeva (Pāli: pubbadeva), meaning "ancient gods."
The Asuras formerly lived in the Trāyastriṃśa world on the peak of Sumeru with the other gods of that world. When Śakra became the ruler of that world, the asuras celebrated by drinking a lot of Gandapāna wine, a liquor so strong that Śakra forbade the other gods to drink it. Weakened by their drunkenness, the asuras could not resist when Śakra had the whole lot of them thrown over the edge of Trāyastriṃśa into what would become the Asura-world at the base of Sumeru. A tree grows there called Cittapātali; when the asuras saw it blossom, they saw that it was different from the Pāricchattaka (Sanskrit: Pāriyātra) tree which had grown in their old home, and they knew that they were dispossessed.
They now meditated on war. In armor and weapons, they climbed up the steep slopes of Sumeru "like ants." Śakra set out to meet them, but was forced to retreat because of their numbers. Passing through the forest where the garuḍas live on his flying chariot, Śakra saw that his passage was destroying the nests of the garuḍas and ordered his charioteer Mātali to turn back. When the pursuing asuras saw Śakra turn about, they felt certain that he must be coming back with an even larger army, and they fled, ceding all the ground they had gained.
Despite their many wars, there was eventually a partial concord between the Trāyastriṃśa gods and the asuras. This came about because Śakra fell in love with Sujā (also known as Shachi), daughter of the Asura chief Vemacitrin. Vemacitrin had given Sujā the right to choose her own husband at an assembly of the Asuras, and she chose Śakra, who had attended disguised as an aged Asura. Vemacitrin thus became Śakra's father-in-law.
The placement of the asura realm in Buddhist cosmology varies among traditions. Sometimes the asura realm is recognized as one of happiness, existing beneath the worlds of the devas and humans. In other schemes, it is viewed as a fourth addition to the usual three evil paths that make up the animal realm, ghost realm and hell realm.
In schools that recognize the desire realm as consisting of five realms, the asura realm tends to be included among the deva realm. In Tibetan Buddhism, the addition of the asuras in the six-world bhavacakra was created in Tibet at the authority of Je Tsongkhapa.
The Ekottara Āgama and the Saddharmasmṛtyupasthāna Sūtra explain that asura are divided among the realms of ghosts and animals. In the former case, they are powerful, high-ranking demons reminiscent of gods such as Māra. In the latter case, they are like fearsome beasts that live 84000 yojanas beneath the ocean floor.[note 1]
The leaders of the asuras are called asurendra (Pāli: Asurinda, 阿修羅王; lit. "Asura-lord"). There are several of these, as the Asuras are broken into different tribes or factions. Among them are the bow-wielding Dānaveghasa Asuras, and the terrible-faced Kālakañjakas.
In Pali texts, names that are found include Vepacitti, Rāhu (believed to be synonymous with Verocana), Pahārāda, Sambara, Bali, Sucitti, and Namucī. According to Buddhaghosa, the three primary leaders were Vepacitti, Rāhu and Pahārāda.
Mahayana literature tends to recognize four primary leaders, whose biographies are explained in detail in both the Saddharmasmṛtyupasthāna Sūtra and the Daśabhūmika Sūtra. According to this tradition, these asuras live 84,000 yojanas beneath the ocean floor on the northern side of Mount Sumeru, which are divided into four layers. The names of places below are derived from Japanese.
According to the Lotus Sutra, the four leaders of the asura took refuge in the Buddha after hearing his sermon.
The asura were said to be in possession of a war drum called Ālambara, which sounded like the peal of thunder. It was created from the claw of a giant crab named Kulīradaha. It has since been repurposed by Śakra.
Mahayana texts also mention a stringed instrument belonging to the asura rendered in Chinese as 阿修羅琴 (lit. "asura harp").