Throughout the Bengal region the officially recognized unit of rural settlement is known as a mauza or "revenue village," which has surveyed boundaries determined during the British imperial period for purposes of taxation and general administration. There are more than 40,000 such villages in West Bengal, and some 68,000 in Bangladesh, but it is important to recognize that these officially designated villages do not necessarily always correspond to actual rural communities as locally and socially defined. Peasant communities range from 100 to 1,000 people, and a typical village in the low-lying Bengal delta consists of one or more hamlets ( para ) of Peasant homesteads ( bari ) built on land deliberately raised so as to avoid monsoon flooding. Along canals and other water-ways the pattern of settlement is more linear, and in areas of the country where monsoon inundations are especially great the pattern tends to be more dispersed. Peasant homesteads are usually composed of extended families, broken down into households most often consisting of a man and his dependents, who form an independent landholding and/or cultivating and consuming unit. Interspersed throughout one finds a network of periodic rural markets, and in the multivillage area served by each local market—what some anthropologists have called the "standard marketing area"—the market functions not only as the focus of commercial activity but also as the social and political center that unites the village communities served by the market into a certain degree of wider Regional identity. Dwellings are most commonly constructed from the dense mud of the Bengal Delta and local, Indigenous construction engineering is sometimes sophisticated enough to allow the raising of homes of two and three stories in height. Animal shelters and fruit-bearing trees are Common fixtures in a homestead area, and the excavation of mud for construction often results in a human-made pond that serves the residents as a source of fish as well as water for bathing and laundering. Thatch grass typically provides roofing, but wealthier families can afford roofs of corrugated iron; the poorest families often have homes primarily made of bamboo only.