The Iroha is a Japanese poem, probably written in the Heian era (AD 794–1179). Originally the poem was attributed to the founder of the Shingon Esoteric sect of Buddhism in Japan, Kūkai, but more modern research has found the date of composition to be later in the Heian Period. The first record of its existence dates from 1079. It is famous because it is a perfect pangram, containing each character of the Japanese syllabary exactly once. Because of this, it is also used as an ordering for the syllabary.
The first appearance of the Iroha, in Konkoumyousaishououkyou Ongi (金光明最勝王経音義), was in seven lines: six with seven morae each, and one with five. It was also written in man'you-gana.
Structurally, however, the poem follows the standard 7-5 pattern of Japanese poetry (with one hypometric line), and in modern times it is generally written that way, in contexts where line breaks are used.
Authorship is traditionally ascribed to the Heian era Japanese Buddhist priest and scholar Kuukai. It is said that the iroha is a transformation of these verses in the Nirvana Sutra:
諸行無常 是生滅法 生滅滅已 寂滅為楽
which translates into
All acts are impermanent That's the law of creation and destruction. When all creation and destruction are extinguished That ultimate stillness (nirvana) is true bliss.