There are a number of scripts which have never been deciphered, despite much effort. Perhaps the most famous are the script of the Indus Valley civilization, and Etruscan. The Indus River civilisation predates other literate civilisations on the Indian subcontinent, going back to about 2500. Their cities of Mohenjo-Daru and Harappa were well-planned, with good drainage. The script is found on seal stones, terracotta, bronze, bone and ivory. All are brief, and the language is unknown.