The Kashkulis are a subtribe of the Kashghai tribe in southern Persia, and they are generally regarded as the best rug knotters. The knotting is exquisite for a tribal standard, where wefts of cotton or silk can be found. The pile is always wool, and mostly small sizes are produced. A wide range of patterns can be seen, but the most characteristic is an adaptation of the classical Herati or fish pattern, and a prayer arch pattern with cypress trees on either side. A wide range of colours is used. Sherkat is the designation for a select series of rug types that are knotted in special workshops as part of a state-controlled project, the purpose of which is to support and thereby preserve the production of fine classical Persian rug patterns.