Nearchus, who commanded
Alexander the Great's naval fleet, mentioned a hilly island by the name of
Morontobara and an adjacent flat island named
Bibakta, which colonial historians identified as Karachi's
Manora and
Keamari (or
Clifton), respectively, based on Greek descriptions. Both areas were island until well into the colonial era, when silting in led to them being connected to the mainland. In 711 CE,
Muhammad bin Qasim conquered the
Sindh and Indus Valley and the port of
Debal, from where he launched his forces further into the Indus Valley in 712. Some have identified the port with Karachi, though some argue the location was somewhere between Karachi and the nearby city of
Thatta. Under
Mirza Ghazi Beg, the
Mughal administrator of Sindh, the development of coastal Sindh and the
Indus River Delta was encouraged. Under his rule, fortifications in the region acted as a bulwark against
Portuguese incursions into
Sindh. Karachi is also mentioned in the sixteenth century
Turkish treatise ''
Mir'ât ül Memâlik'' (Mirror of Countries, 1557) by the
Ottoman captain
Seydi Ali Reis, which warns sailors about whirlpools and advises them to seek safety in "
Kaurashi" harbour if they found themselves drifting dangerously. In 1728, heavy rains silted up the harbour at
Kharak, forcing merchants to relocate to the area of modern Karachi. 19th-century Karachi historian
Seth Naomal Hotchand recorded that a small settlement of 20–25 huts existed along the Karachi Harbour that was known as
Dibro, which was situated along a pool of water known as
Kolachi-jo-Kun. In 1725, a band of
Balochi settlers from
Makran and
Kalat had settled in the hamlet after fleeing droughts and tribal feuds. A new settlement was built in 1729 at the site of
Dibro, which came to be known as
Kolachi-jo-Goth ("The village of
Kolachi"), which grew into the modern city. The gate facing the sea was called "
Kharadar" (
salt gate), and the gate facing the Lyari River was called "
Mithadar" (
sweet gate). From 1729 to 1783 the strategic location of Kolachi saw the town change hands several times between the
Khans of
Kalat and the rulers of Sind. In 1783, after two prolonged sieges the town fell to the
Talpur Mirs of Sind, who constructed a fort mounted with cannons on
Manora island at the harbour entrance. The
British East India Company captured Karachi on 3 February 1839 after opened fire and quickly destroyed
Manora Fort, which guarded Karachi Harbour at
Manora Point. Karachi was recognized for its strategic importance, prompting the British to establish the
Port of Karachi in 1854. Karachi rapidly became a transportation hub for British India, owing to the newly built port and rail infrastructure, as well as the increase in agricultural exports from the opening of productive tracts of newly irrigated land in
Punjab and interior Sindh. At the outbreak of the
American Civil War, Karachi Harbour became an important cotton-exporting port, with
Indus Steam Flotilla and
Orient Inland Steam Navigation Company established to transport cotton from interior Sindh to the harbour, and onwards to textile mills in England. With the completion of the
Suez Canal in 1869, Karachi's position as a major port increased even further. In 1878, the British Raj connected Karachi with the network of
British India's vast railway system. In 1887, Karachi Port underwent radical improvements with connection to the railways, along with expansion and dredging of the port, and construction of a breakwater. == Island settlements ==