Regulations for housing were concerned principally with status, economy and fire prevention, although fire was much less of a problem for the provincial administrators than it was for those responsible for Edo. As one of the two hundred and sixty domains which comprised the governmental structure of Tokugawa Japan, Choshu was a theoretically autonomous administrative unit responsible for the drafting and execution of its own laws and regulations. Laws and regulations issued in the domains, as in Choshu, in principle took several forms. Existing research into architectural regulations for the han has revealed no comprehensive document dealing with the control of architectural elements and style. Hagi in its initial phase of development appears to have employed the concepts of social organisation and urban planning in the Keicho Period, and to have used site planning principles and architectural models common to the domains of Mori Terumoto’s peers.