The land of modern-day Mumbai is geographically different than it appeared in earlier centuries. Formerly, it was a cluster of islands - principally (although not completely) the seven pictured here:
Mahim: to the west of Parel and north of Worli, took its name from the Mahim river and was the capital of a 13th-century kingdom founded by Raja Bhimdev.
Parel: North of Mazagaon and called by many other names, including Matunga, Dharavi and Sion. The original population was predominantly Koli.
Worli: north of Bombay was seperated from it by the Great Breach, which extended westwards almost to Dongri.
Mazagaon: a Koli settlement, to the east of Bombay Island, was seperated from it by Umarkhadi and Pydhonie.
Bombay: the main harbour, and the nucleus of the British fort from which the modern city grew, it stretched from Dongri on the east to Malabar Hill on the west.
Old Woman’s Island: (alternatively, Old Man’s Island) a small rock between Colaba and Bombay, whose name is a corruption of the Arabic name Al-Omani, after deep-sea fishermen who plied the waters up to the Gulf of Oman.
Colaba: whose name is a corruption of the Koli name Kolbhat.
NOTE: This image does not include all the islands which now comprise Mumbai (such as Salsette, a large northern island). It does, however, represent what is today referred to as "The Seven Islands."
Credits
Image, and quoted passage, online courtesy 7islands.