Gyosen

...Tōzōki are candy-colored rice dumplings made from glutinous rice, while Rehmannia candy is candy. Originally it referred to a decoction of Rehmannia root, which was used as a medicine, but it eventually came to refer to the candy that was made by adding it to starch syrup, and then it came to refer to the candy itself without Rehmannia root, and was corrupted to "gyousen." In the early Edo period, the candy from Kikuichimonjiya in front of Tofukuji Temple in Kyoto, Katsura candy from Katsura no Sato, and Hirano candy in Osaka were famous, and these were called "kudari candy" or "kudari gyousen" in Edo and highly valued....

*Some of the terminology explanations that mention "gyosen" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…糖粽のほうはあめ色になったもち米のちまきであるが，地黄煎のほうはあめである。もともとは薬とされたジオウの煎汁をいうのだが，やがてそれを水あめに加えたものをいうようになり，さらにジオウを入れぬあめそのものの呼称になり，なまって〈ぎょうせん〉ともいった。江戸初期，京都では東福寺門前の菊一文字屋のものや桂の里の桂あめ，大坂では平野あめなどが有名で，これらは江戸で〈下（くだ）りあめ〉〈下りぎょうせん〉と呼んで珍重された。…

※「ぎょうせん」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報