There are numerous reliable, authentic sources one may access to gain a clearer picture of how karate & kata were practiced in Okinawa during its peak in the mid-1800’s and what significant factors changed during its introduction into Japan during the 1920’s and subsequent global popularity.
Old style Okinawan karate (Toudi or Tode) was totally based on self-defense applications – there were no tournaments with trophies for long range sparring or a kata performance before judges. Rather a respected master taught small groups brutal, effective & holistic methods of self-defense, primarily through the practice of standardized two-person training drills (Tegumi). Kata evolved as a way for an already competent practitioner to remember the principal techniques of the partner drills when practicing alone – kata in & of itself did not teach the application, only preserved its details.
The five Pinan or Heian kata were invented in 1907 by Itosu Ankoh specifically to provide physical fitness & mental discipline for the 5 years of primary school Okinawan children attended around the ages 11-16 (much like Judo & Kendo in Japan). Itosu gathered sets of techniques from a variety of older kata (Koshokun) to remake a more uniform, consistent family of 5 kata, one of which was practiced for each year of school – like aerobics without music. The original applications & two person drills which had trained the defensive themes were never emphasized, although today we can reapply these concepts to the Pinan kata to reveal practical, brutal & effective bunkai. Many researchers have suggested that the more dangerous aspects of karate technique & application were intentionally altered or left out considering to whom (school children) and why (for fitness & discipline only) it was being taught. Of course, small groups under various masters were still practicing classical karate.
Once introduced to Japan during the 1920’s, few of the Okinawan karate experts (Master Funakoshi of Shotokan, Master Miyagi of Goju & Master Kenwa Mabuni of Shito) who likely knew many of the tegumi & application principles for the old kata ever commonly taught them. The nature of karate as it evolved in Japan had vastly different aims than the classic Okinawan self-defense tradition – Japanese Budo traditions (Judo, Kendo, modern Karate) were modernized & highly simplified to provide rigorous physical training, mental discipline, nationalistic zeal & sporting competition. Thus, the modern Japanese based (and most Okinawan) karate styles were virtually unaware of the older defensive grappling, throwing & striking kata applications, and perfected & promoted karate as a martial art relying mostly on long range, powerful hand & foot attacks (and by default, defending against the same).