The Jewel River in Musashi Province (Musashi Tatsukuri) is known as one of the Six Jewel Rivers (Mu Tamagawa) often depicted as a subject of allusive picture (mitate-e) of beauties by many artists.
This river is written in a poem by an unknown poet contained in vol. 14 of the Man'yoshu (Collection of a Myriad Leaves), the anthology of classic verse written before 760:
Tamagawa ni sarasu tetsukuri sarasarani mukashi no fude to sarani omowazu
(When I bleach the softest hand-made cotton in the Jewel River, I recall the love letter I once wrote to you.)