Sion is the last locality within the City limits of Mumbai. The Marathi name for Sion is Sheev (शीव), which means boundary or limit. In the 17th century the village formed the boundary between Mumbai and Salsette Island.
In 1543, the Portuguese took possession of the islands of Bombay by force. They called it Sião. The Portuguese gave the Jesuit priests the sole ownership of some of these islands. The Jesuits built a chapel on the hill (near the present-day railway station) and named it after Mount Zion (Sion) in Jerusalem.