The jibutsudo (room where Buddhist images and ancestors' mortuary tablets are enshrined) called Togudo in the Higashiyama dono (Ginkaku-ji) run by Ashikaga Yoshimasa still exists there. One of the rooms in this building, is Dojinsai, a yojohan (four-and-a-half) mat room with an open hearth which is thought to be the origin of the tea room. Yoshimasa used to drink tea in this room. It is said that Shuko was invited here and heard about the wabi-cha (tea of quiet taste) of the machishu (lit. 'townspeople', upper-class merchants) served in a soan (thatched hut) tea house. This yojohan was shoin style, so it had no toko (alcove). However it was this kind of yojohan whose design was gradually abbreviated and its simplified form became Shuko's yojohan. Takeno Joo took the simplification even further and changed it into a yojohan with clay walls.
However, that yojohan was for use with karamono (Chinese things) and had no connection with people who did the simple kind of tea in which no Chinese things were used.
So Sen no Rikyu made the revolutionary change to a tea room that was exactly as the word soan implied, a tiny two mat space in which only wabi-cha could be done. This can be seen in the Tai-an tea room at Myoki-an a Rinzai sect temple in Yamazaki in Kyoto. Hideyoshi was invited to this tea room and completely captivated, so that he built a two mat tea room in Osaka Castle. In this way wabi-cha and soan-cha became central to chanoyu.