Karate: The History and Practice of the Art/Heian Kata
The Heian kata are five forms taught in many karate styles. The exact form varies by style as they have evolved from their original design. In some styles they are known as the Pinan kata. The kata are believed to have been developed in Okinawa by Anko Itosu and contain many sequences that are similar to Kusanku albeit in slightly modified form.
Gichin Funakoshi further developed the kata to make them appropriate for teaching to children in Japan. This involved removing some of the most dangerous techniques or replacing them with less dangerous techniques. For example, side thrust kicks were replaced with side snap kicks which are much less likely to cause a serious leg injury if applied to an opponents knee.
The give kata are called Shodan, Nidan, Sandan, Yondan, and Godan and are usually taught in this sequence.