Harappan script is a corpus of symbols produced by the Indus Valley Civilization during the Kot Dijiand Mature Harappanperiods between the 26th and 20th centuries BC. Most inscriptions are extremely short. It is not clear if these symbols constitute a scriptused to record a language, and the subject of whether the Indus symbols were a writing systemis 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 CunninghamSince 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.