In the historic period prior to 1833 the Pawnee bands were settled in four groups of villages in valleys along the Platte River. Villages were large and relatively permanent, and consisted of clusters of earthlodges surrounded by fields. In the nineteenth century some villages were surrounded by a sod wall three to four feet high for defensive purposes. Earthlodges were circular and constructed of a log frame plastered over with layers of grass and packed earth. Lodges varied in size according to the number of occupants, but averaged fifteen feet in height and forty feet in diameter. In the summer the occupants of the earthlodge moved outdoors and slept under a brush arbor. Tipis of bison hide were used for shelter on the hunt.