Originally, in the time of the Man’yōshū (latter half of the eighth century AD), the term tanka was used to distinguish “short poems” from the longer chōka ( “long poems”). In the ninth and tenth centuries, however, notably with the compilation of the Kokinshū, the short poem became the dominant form of poetry in Japan, and the originally general word waka became the standard name for this form. Japanese poet and critic Masaoka Shiki revived the term tanka in the early twentieth century for his statement that waka should be renewed and modernized.
The poem consists of 31 syllables and is often written in English and other Roman languages in five lines with a 5-7-5-7-7 syllable count. Either Is acceptable.
The 5-7-5 is known as the kami-no-ku (upper phrase) and the 7-7 is called the shimo-no-ku is the (lower phrase).
Here is an example:
On the white sand
of a beach of a small island
in the Eastern sea.
I, my face streaked with tears,
am playing with a small crab.
Tanka in English
The composition and translation of tanka in English begins at the end of the nineteenth century in England and the United States. Translations into English of classic Japanese tanka (traditionally known as waka) date back at least to the 1865 translation of the classic Ogura Hyakunin Isshu (c. early 13th century); an early publication of originally English tanka dates to 1899. In the United States, the publication of tanka in Japanese and in English translation acquires extra impetus after World War II, and is followed by a rise of the genre’s popularity among native speakers of English.
**With thanks to Wikipedia for some of the text.