Final answer:
Adobe, made of clay and straw, is the building material often used in regions with scarce rainfall due to its suitability for dry climates and ability to conserve resources.
Step-by-step explanation:
The building material commonly used in regions with little rainfall, which is made of clay and straw, is known as adobe. This material is ideal for dry climates because adobe walls can be protected by whitewashing them regularly, which prevents deterioration during the rare occurrences of rain. In contrast, materials like concrete blocks or gypsum board wouldn't fare as well without regular maintenance in such environments. Traditional adobe constructions have nearly flat roofs to help collect scarce water, and the materials' thermal properties are well-suited for hot, dry regions, conserving both heat and resources.
In areas like Babylonia, where clay was abundant and stone was scarce, the use of mud brick was prevalent. Elaborate techniques in brick making and building, including buttresses and drainage systems, helped to manage the few rainstorms that did occur. These historical practices underscore how regional resources and climate have long influenced building materials and architectural styles, from ancient times through to contemporary methods that integrate new technologies and materials to address environmental and design challenges.