The karado, which came from the Continent (especially from China), had been improved from the large and heavy solid timber in the Horyu-ji Temple in Nara, to the sangarado during the Kamakura period, and was technically completed to reduce weight.
大陸伝来の唐戸は、奈良法隆寺の一枚板の重厚長大な扉から、鎌倉時代の桟唐戸に至って、建具の軽量化という技術的完成をみるに至った。