The history of measurement systems in India begins in early Indus Valley civilisation with the earliest surviving samples dated to the 5th millennium BCE. Since early times the adoption of standard weights and measures has reflected in the country's architectural, folk, and metallurgical artifacts. A complex system of weights and measures was adopted by the Maurya empire (322–185 BCE), which also formulated regulations for the usage of this system. Later, the Mughal empire (1526–1857) used standard measures to determine land holdings and collect land tax as a part of Mughal land reforms. The formal metrication in India is dated to 1 October 1958 when the Indian Government adopted the International System of Units (SI). Early history Standard weights and measures were developed by the Indus Valley Civilization. The centralised weight and measure system served the commercial interest of Indus merchants as smaller weight measures were used to measure luxury goods while larger weights were employed for buying bulkier items, such as food grains etc. Weights existed in multiples of a standard weight and in categories. Technical standardisation enabled gauging devices to be effectively used in angular measurement and measurement for construction. Uniform units of length were used in the planning of towns such as Lothal, Surkotada, Kalibangan, Dolavira, Harappa, and Mohenjo-daro. The weights and measures of the Indus civilisation also reached Persia and Central Asia, where they were further modified. Shigeo Iwata describes the excavated weights unearthed from the Indus civilisation: The significance of a binary system of weights is that it allows an indivisible weight (eg. a gold coin or piece of jewelry) to be measured on a balance with the minimum number of weights, while the decimal system of weights and measures allows the minimum number of weights/measures to be used for bulk items by allowing repeat measures to be counted on the fingers. Rulers made from Ivory were in use by the Indus Valley Civilisation prior to 1500 BCE. Excavations at Lothal (2400 BCE) have yielded one such ruler calibrated to about . Ian Whitelaw (2007)—on the subject of a ruler excavated from the Mohenjo-daro site—writes that: 'the Mohenjo-Daro ruler is divided into units corresponding to 1.32 inches (33.5 mm) and these are marked out in decimal subdivisions with amazing accuracy—to within 0.005 of an inch. Ancient bricks found throughout the region have dimensions that correspond to these units.' The Indus civilisation constructed pan balances made of