The kimono's left-over-right wrap was fixed by law in 718
Every living kimono wearer wraps the left side over the right; only the dead are dressed the other way. That rule traces back to the Yōrō legal code of 718, which copied Chinese fashion. Japan's national dress began as imported Chinese clothing and slowly became something distinctly Japanese.
The word kimono simply means thing to wear. The garment has square sleeves, a rectangular body and a wrapped front, held with a broad sash called an obi and usually paired with zōri sandals and tabi socks. It is sewn to a fixed pattern, normally cut from a tanmono, a single slim roll of fabric. Styles differ for men, women and children and shift with the occasion, the season and the wearer's age. The skill of putting one on properly has its own name, kitsuke.
Its roots lie in China. During the Kofun period, from 300 to 538 CE, envoys, migrants and missions to the Tang court made Chinese dress hugely fashionable among Japan's elite, and the oldest tie-dyed shibori fabrics preserved at the Shōsōin came from China because Japan could not yet make them. Early court sleeves were narrow but long enough to hide the fingers, since covering more of the body signalled higher status.
The break came in the Heian period, when Japan stopped sending envoys to Chinese courts. Cut off from imported cloth, the aristocracy developed a homegrown style called kokufū, or national culture, which produced garments such as the layered jūnihitoe. Courtiers and warriors wore a plain white kosode underneath. During the turbulent Sengoku era of the late Muromachi period, that humble undergarment became an elaborate outer robe, the direct ancestor of today's kimono; until the Edo period, garments of this kind were still called kosode.
Once Japan's everyday clothing, the kimono is now worn mostly for occasions. The light cotton yukata appears at summer festivals, and more formal versions at weddings, funerals and graduations. Geisha and maiko wear kimono for work, and sumo wrestlers must wear one whenever they appear in public. Despite its fussy reputation, the garment has enjoyed revivals in recent decades and still turns up as fashion.
Source: Kimono
