After the collapse of the Gupta Empire (around the same time as that of the Roman Empire), India spent decades under the rule of regional kingdoms. In the early 7th century, a regional prince named Harsha ascended the throne of one of these kingdoms, and quickly carved out an empire. While his empire was not as large as the Guptas, he controlled a great deal of the Gangetic plain and brought India into a cultural and artistic revival. But after his death in 646, squabbling administrators pulled his kingdom apart, throwing northern India back into political chaos.

In 711, a new force entered this political mess. The kingdom of Sind attacked Muslim traders, and the Umayyad Caliphate launched an attack on Sind. A young general named Muhammad ibn Qasim became commander of the Umayyad army. After several successful battles and sieges, ibn Qasim annexed the kingdom of Sind.

The first Muslim invasion had little effect on Indian society. As the Muslims soon found that they could not eradicate the Hindus and Buddhists in the area, they accepted them as dhimmis, even though the Indian religions did not share the Bible with Christians, Jews, and Muslims. The Muslims spent very little time trying to convert the Indian peoples to their religion, and the Hindus and Buddhists showed little interest in Islam.

While the Muslims had little effect on India, the culture of the conquered people had immense effect on the Umayyads. Indian works on algebra and geometry were incorporated. The so-called Arabic numerals were actually devised in India and adopted by the Muslims. Indian instruments for astronomy were improved upon, and Indian medical discoveries surpassed those of the Greeks and Arabs. The Umayyads also adapted Indian music, and some tales from the "Arabian Nights" might have been based on ancient Indian stories. Muslims in Sind often adopted Indian dress, food, and architecture.

The first Muslim rulers in India gradually lost power as the Empire changed hands from the Umayyads to the Abbasid Dynasty. Hindu princes ate away Muslim holdings in India. In 962, a Turkish slave dynasty under Mahmud of Ghazni began raids into India for wealth and to spread Islam. In the last decades of the 12th century, a Persian military commander named Muhammad of Ghur turned raids into invasions and quickly brought the Indus valley and northern India under his control. After Muhammad was assassinated in 1206, Qutb-ud-din Aibak seized power. He moved the capital to Delhi and for the next three centuries, Muslims ruled northern India as sultans of Delhi.

During the second invasion, India began to see many more conversions to Islam. Merchants and Sufi mystics spread the religion, and the Sufi gifts of organization were especially helpful. The majority of converts were Buddhists or Hindus from the lower caste groups. The promise of social equality, a strong religion, and escape from the head tax on non-believers attracted many to Islam.

While Muslims attracted the low caste groups to their religion, the high caste groups rejected the religion. They did trade with the Muslims, serve as soldiers, and work as administrators, but they remained socially aloof and saw the Muslims as infidels. Hindus were fairly certain that Islam would be absorbed into Hinduism, but though this did not happen, Islam adopted many Hindu characteristics. Islam was originally highly egalitarian, but this society slowly developed into a caste system similar to the one existing in India at the time. Muslims adopted Indian dress and food. The status of women was also severely degraded: women were married at younger ages, widows were not allowed to remarry, and the ritual of sati was adopted in some places. Though the Muslims did have some effect on India, Indian culture and learning had a much greater effect on Islam.