The Indus script (also Harappan script) is a corpus of symbols produced by the Indus Valley Civilization during the Kot Diji and Mature Harappan periods between the 35th and 20th centuries BC. Most inscriptions are extremely short. It is not clear if these symbols constitute a script used to record a language, and the subject of whether the Indus symbols were a writing system is controversial. In spite of many attempts at decipherment, it is undeciphered, and no underlying language has been identified. There is no known bilingual inscription. The script does not show any significant changes over time. The first publication of a seal with Harappan symbols dates to 1873, in a drawing by Alexander Cunningham. Since then, over 4,000 inscribed objects have been discovered, some as far afield as Mesopotamia. In the early 1970s, Iravatham Mahadevan published a corpus and concordance of Indus inscriptions listing 3,700 seals and 417 distinct signs in specific patterns. The average inscription contains five signs, and the longest inscription is only 17 signs long. He also established the direction of writing as right to left. Some early scholars, starting with Cunningham in 1877, thought that the system was the archetype of the Brāhmī script. Cunningham’s ideas were supported by scholars, such as G.R. Hunter, S. R. Rao, F. Raymond Allchin, John Newberry, Iravatham Mahadevan, Krishna Rao, Subhash Kak some of whom continue to argue for an Indus predecessor of the Brahmic script.