Itosu is reported to have learned the Karate Kata Tekki Shodan from Sokon Matsumura, who learned it from a Chinese man living in Tomari. Itosu is thought to have changed the original kata. The form is so important to old style karate that Kentsu Yabu (a student of Itosu) often told his students ‘Karate begins and ends with Naihanchi’ and admonished his students must practice the kata 10,000 times to make it their own. Before Itosu created the Heian kata, Tekki Shodan would traditionally be taught first in Tomari-te and Shuri-te schools, which indicates its importance. Gichin Funakoshi learned the kata from Anko Asato. Funakoshi renamed the kata Tekki (Iron Horse) from Naihanchi in reference to his old teacher, Itosu, and the form’s power.
The oldest known reference to Naihanchi are in the books of Motobu Choki. He states the kata was imported from China, but is no longer practiced there. Motobu learned the kata from Sokon Matsumura, Sakuma Pechin, Anko Itosu and Kosaku Matsumora. Motobu taught his own interpretation of Naihanchi, which included te (Okinawan form of martial arts which predates karate) like grappling and throwing techniques.
In the earlier days of karate training, it was common practice for a student to spend 2-3 years doing nothing but Tekki Shodan, under the strict observation of their teacher. Motobu Choki, famous for his youthful brawling at tsuji (red-light district), credited the kata with containing all that one needs to know to become a proficient fighter.
Modern day exponents still teach the close range techniques associated with this Kata. The following 10 minute taster video shows Iain Abernethy demonstrating a couple of his flow drills derived from the Kata
Even from this short demo it’s obvious what possibilities there are within Tekki Shodan for clinching, close range striking and limb control.