The Indus or Harappa script collection of symbols used in the Indus valley in northern India between about 3,500 and 2,000 BC. Some believe that these symbols are non-linguistic, while others argue that they represent a Dravidian language.
Since 1875 more than 4,000 objects inscribed with this script have been found. Most inscriptions are short and consist of five symbols on average, with 17 in the longest one. Inscriptions are mostly on flat, rectangular stamp seals, and also on tools, tablets, ornaments and pottery. 417 distinct symbols have been identified, and the direction of writing is thought to be right to left, and sometimes boustrophedon.
Many people have tried to decipher the Indus script, but none have succeded so far, or at least none have procuded a generally-accepted decipherment. Some believe that the Indus script was used to write a Dravidian language, others that it was used to write an ancestor of Sanskrit.