The Amazigh peoples (commonly called "Berbers" in English) are a linguistically and ethnically diverse group of peoples who constitute the indigenous (pre-Arab) inhabitants of North Africa. They continue to represent a large part of the population in Morocco. In addition to any local traditions of architecture, Amazigh peoples adapted the forms and ideas of Islamic architecture to their own conditions and in turn contributed to the formation of Western Islamic or "Moorish" art, particularly during their political domination of the region over the centuries of Almoravid, Almohad, and Marinid rule. Given the intermixing of peoples and settlements in the region over the centuries, it is not always easy to separate Amazigh and non-Amazigh architectural features; however, there are architectural types and features associated with predominantly Amazigh areas of Morocco (particularly the rural Atlas mountains and Saharan regions) which are sufficiently distinctive to constitute their own characteristic styles. Because the relevant structures are made of rammed earth or mud-brick, which requires regular maintenance for preservation, the existing examples can rarely be dated reliably past the 19th or even 20th centuries. Nonetheless, some characteristics of Berber architecture in North Africa – such as the regional forms of mosques – have been established for roughly a millennium. Structures such as agadirs (fortified granaries) and qsūr or qsars (fortified villages; often spelled ksar in singular and ksour in plural) are prominent traditional features of Amazigh architecture in Morocco. Likewise, the landscapes of the Atlas mountains and oases regions of Morocco are marked by numerous kasbahs – or tighremt in Amazigh languages – which in this case refers to tall, fortified structures acting as forts, warehouses, and/or fortified residences. These can in turn be decorated with local geometric motifs carved into the mud-brick exteriors. French The Treaty of Fes established the French Protectorate in 1912. The French resident general Hubert Lyautey appointed Henri Prost to oversee the urban development of cities under his control. One important policy with long-term consequences was the decision to largely forego redevelopment of existing historic cities and to deliberately preserve them as sites of historic heritage, still known today as the "medinas". Instead, the French administration built new modern cities (the Villes Nouvelles) just outside the old cities, where European settlers largely resided with modern Western-style amenities. This was part of a larger "policy of association" adopted by Lyautey which favoured various forms of indirect colonial rule by preserving local