A Tabriz rug is a type in the general category of Persian carpets from the city of Tabriz, the capital city of East Azerbaijan Province in north west of Iran totally populated by Azerbaijanis. It is one of the oldest rug weaving centers and makes a huge diversity of types of carpets. The range starts at Bazaar quality of 24 raj (Number of knots per 7 cm of the widths of the rug) and on up to the incredibly fine 110 raj. Raj are the units of knot density (it shows the fitness of the rug which based on the number of strings used for the foundation of the rug. Strings materials are usually made of cotton or silk which is used for very fine rugs).