<P> Islam in South Asia existed in communities along the Arab coastal trade routes in Sindh, Bengal, Gujarat, Kerala, and Ceylon as soon as the religion originated and had early gained acceptance in the Arabian Peninsula, though the first incursion by the new Muslim successor states of the Arab World occurred around 636 CE or 643 AD, during the Rashidun Caliphate, long before any Arab army reached the frontier of India by land . </P> <P> Uthman b . Abul As Al Sakifi, governor of Bahrain and Oman, sent out ships to raid Thane, near modern - day Mumbai, while his brother Hakam sailed to Broach and a third fleet sailed to Debal under his younger brother Mughira either in 636 CE or 643 AD . According to one source all three expeditions were successful, however, another source states Mughira was defeated and killed at Debal . These expeditions were sent without the Caliph Umar's consent, and he rebuked Uthman, saying that had the Arabs lost any men the Caliph would have killed an equal number of men from Utham's tribe in retaliation . The expeditions were sent to attack pirate nests, to safeguard Arabian trade in the Arabian Sea, and not to start the conquest of India . </P> <P> The kingdoms of Kapisa - Gandhara in modern - day Afghanistan, Zabulistan and Sindh (which then held Makran) in modern - day Pakistan, all of which were culturally and politically part of India since ancient times, were known as "The Frontier of Al Hind". The first clash between a ruler of an Indian kingdom and the Arabs took place in 643 AD, when Arab forces defeated Rutbil, King of Zabulistan in Sistan . Arabs led by Suhail b . Abdi and Hakam al Taghilbi defeated an Indian army in the Battle of Rasil in 644 AD at the Indian Ocean sea coast, then reached the Indus River . Caliph Umar ibn Al - Khattab denied them permission to cross the river or operate on Indian soil and the Arabs returned home . </P> <P> Abdullah ibn Aamir led the invasion of Khurasan in 650 AD, and his general Rabi b . Ziyad Al Harithi attacked Sistan and took Zaranj and surrounding areas in 651 AD while Ahnaf ibn Qais conquered the Hepthalites of Herat in 652 AD and advanced up to Balkh by 653 AD . Arab conquests now bordered the Kingdoms of Kapisa, Zabul and Sindh in modern - day Afghanistan and Pakistan . The Arabs levied annual tributes on the newly captured areas, and leaving 4,000 men garrisons at Merv and Zaranj retired to Iraq instead of pushing on against the frontier of India . Caliph Uthman b . Affan sanctioned an attack against Makran in 652 AD, and sent a recon mission to Sindh in 653 AD . The mission described Makran as inhospitable, and Caliph Uthman, probably assuming the country beyond was much worse, forbade any further incursions into India . </P>

When did arab invade on india first time