Permanent castles in the Sengoku Period are generally said to be "tsuchi no shiro (castles made of soil)" in Togoku (eastern part of Japan) and "ishi no shiro (castles made of stone)" in Saigoku (western part of Japan).
戦国時代における永久築城は、一般的に、東国においては土の城、西国においては石の城と称される。