The Indus Dictionary Project
This is a crossroads where three of the exits are blocked, and the fourth exit is marked with a mountain range. Hence, Mahadevan's sign number 151 translates as: 'sole route through the
Mohenjo-daro: Seal: M-261 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 64: Collections in India: Suomalainen Tiedeakatemia.
There is only one extant example of this Indus sign.
Indus Script Sign Number 151: Sign List of the Indus Script: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.