Fukuchiyama was a city where sericulture was active for a long time due to the mulberries resistance to repeated overflows of the Yura-gawa River into Fukuchiyama in Fukuchiyama City; also the pH value of the Yura-gawa River has shown that its water quality was suitable for yarn-making.
福知山は度重なる福知山市福知山と由良川に対して桑は洪水に強かったことや、由良川の水素イオン指数値が製糸に適した水質であったことなどから、古くから養蚕業が栄えたまちである。