Al-Madhaji (2010) stated that over the course of time, Yemen has been able to provide for the housing needs of its people. According to Bukair & Al-Madhaji (2015) and Al-Sabahi (2005), more research is needed to study sites made from mud. The cities in the region of Hardramaut Valley, Yemen serves as an example of the mud architectural heritage of the country. Smith (2007) presented an urban planning model for traditional cities. The model considers building arrangement and the norm in cities. The author also discussed the importance of political and social factors in terms of urban planning.
Marshall (2012) mentioned that the complexity of cities can be reduced by planning. The author highlighted four types of “organised complexity”, which include “artefactual complexity, system complexity, biological complexity and ecological complexity”. The author stated that complexity in cities stem from the lack of knowledge on the impacts of intervention and the current and future state of the cities.