During the Sengoku Period, Junsho TSUTSUI became a daimyo (Japanese territorial lord) by ruling the majority of the province temporarily, but after he died suddenly and the infant Junkei TSUTSUI succeeded him, the Ochi clan fought back and broke the control of the Tsutsui clan.
戦国時代には筒井順昭が一時国内の大半を平定して戦国大名化を進めるが、順昭が急死して幼少の筒井順慶が後を継ぐと、越智氏らが反撃して筒井氏の支配は解体した。