Muhammad bin Qasim was born around 695, his father died when he was young, so his education was handled by his mother.
One of his close relatives was the Umayyad governor Hajjaj bin Yousef who was instrumental in teaching Muhammad bin Qasim about warfare and governing.
With Hajjaj's patronage, he was made governor of Persia where he put down a rebellion.
At the age of seventeen, he was sent by caliph al-Walid to lead an army into Sindh India.
The Umayyad reasoning for this attack was to rescue some pilgrims that were taken captive by Hindu pirates.
Bin Qasim was successful, rapidly taking all of Sindh and moving into southern Punjab up to Multan.
The forces of Muhammad bin Qasim defeated Raja Dahar, and took his daughters captive (they were sent to Damascus).
The raiders demolished temples, shattered "idolatorous" artwork and killed many men (it took three days to slaughter all the inhabitants of the city of Debal) enslaving the women and children.
On his arrival at the town of Brahminabad he massacred between 6,000 and 16,000 men.
After the violence Qasim attempted to establish law and order in the newly-conquered territory by allowing a degree of religious tolerance.
He was countermanded by Hajjaj who insisted on a more hardline policy.
He also began preparations for an attack on Rajasthan.
In the interim though, Hajjaj bin Yousef died, as did the caliph al-Walid.
The new caliph, Suleiman was a political enemy of Hajjaj and recalled Muhammad bin Qasim using the claims of Raja Dahar's daughters as a pretense (they claimed that bin Qasim had not treated them right - the validity of this claim is questionable).
Bin Qasim was wrapped in oxen hides and returned to Syria. He could have very well not followed the caliphs order, but he did.
Muhammad bin Qasim would die in jail, at the age of twenty.
Bin Qasim's rapid gains at such a young age have led many scholars to speculate on how much he could have achieved had he been given the chance.
Some have written that he may have taken all of South Asia, but whether or not this is valid is debatable.
History of the Khilafah in India
In the year 711CE, Muslim traders were sailing in the Indian Ocean from Ceylon near the coast of Sind. However, the ship was looted and the Muslims were captured and imprisoned. The news reached the capital of the Islamic Khilafah state. Where the Khalifah al-Walid b. �Abdul Malik heard about this. Then he sent a message to Hujjaj b. Yusuf, the Wali (governor) of Baghdad to demand the apologies from the ruler of Sind and rescue the Muslims. An army was dispatched lead by one of the most brilliant sons of this Ummah. The name of this youthful figure occupies a very high position in the hearts of the Muslims especially of the Indian subcontinent. It was upon the shoulders of this man that fell the responsibilities of leading the Islamic Khilafah army into a foreign land. The name of this man was Muhammad b. Qasim al-Thaqafi, the opener of bilad al hind.
When the Islamic Khilafah state army reached Debal (near modern day Karachi), Muhammad b. Qasim and presented his demands to Raja Dahir. The Raja resisted the demand and thus, was inevitably defeated by the Muslims and his kingdom captured.
After this, Muhammad b. Qasim followed up his initial success with further encounters because it is the duty of Muslims to make the word of Allah �azza wa jall the highest. The Islamic Army, driven by the Islamic Aqeedah, penetrated as far as Multan. Within three years, by 714 CE, the whole of Sind and lower Punjab were brought under the rule of the Islamic Khilafah.
In the conquest of the north-western part of the subcontinent of India, the army took the idol worshippers from darkness into the light of Islam. His administration made no distinction between Muslims and non-Muslims. In the conquered territories he reinstated non-Muslim officials to their former positions.
Muhammad b. Qasim told the administrators of the Khilafah, "Deal honestly between people and the State. Fix taxes according to the ability of the people to pay."
It was during the time of Khalifah Hisham b. �Abdul Malik from 724 to 743 CE that the Khilafah State conquered the regions of Kashmir and Kangra. And during 754-75 under the �Abbasid Khalifah Abu Ja�far Al-Mansur, Kandahar was opened and efforts were made to consolidate and spread the frontiers of the Khilafah state in the Indian subcontinent. It was between 786 and 809 CE, during the Khilafah of Harun ar-Rashid that the Islamic Army extended the frontiers of Sind westwards into Gujarat (now presently in India). It was during this time that Muslim soldiers settled down and new cities started to flourish. From this time onwards, large numbers of the Indians were lifted from their baseless social caste structures of disbelief and brought under the shade of global brotherhood. They were guided from the darkness of ignorance and Kufr to the Nur of Islam, worshipping Allah �azza wa jall and discarding their false idol gods. Islam ruled over most of what is known today as India, Pakistan, Kashmir and Bangladesh for over a thousand years.
Contrary to how the Orientalists portray the history of India, we must realise that it was a Wilayah of the Khilafah. Due to negligence of some of the Khulafah it was unsupervised in some periods and left to run by itself. However the ahkam shariah were applied by the rulers and it was part of Dar al-Islam until the British colonised it.
The Muslim historians like Ibn Kathir al-Damishqi (died 774 AH) in his famous work al-Bidayah wan-Nihaya mentioned India as part of Dar al-Islam, he also quoted some ahadith about its conquest. Abu Huraira (ra) narrated: �My true friend, Allah�s Messenger (saw) said, �The armies of this Ummah will be sent to Sindh and India.� If I get the opportunity to participate in it and am martyred then that is one (auspicious) thing, and if I return then I will be the free Abu Hurayrah. The Exalted Lord would have given me freedom from Hell.� [Ahmad]
India remained as a province of the Khilafah throughout the Delhi Sultanate (1205-1526 CE) and Mughal period (1526-1857 CE) except during Akbar�s rule (1556-1605 CE) as he apostatised from Islam and formed a new religion called Deen-e-Illahi.
The Muslims entered Sind, India, in 711 C.E., the same year they entered Spain. Their entry in India was prompted by an attempt to free the civilian Muslim hostages whose ship was taken by sea pirates in the territory of Raja Dahir, King of Sind. After diplomatic attempts failed, Hajjaj bin Yusuf, the Umayyad governor in Baghdad, dispatched a 17-year-old commander by the name Muhammad bin Qasim with a small army. Muhammad bin Qasim defeated Raja Dahir at what is now Hyderabad in Pakistan. In pursuing the remnant of Dahir's army and his son�s supporters (Indian kings), Muhammad bin Qasim fought at Nirun, Rawar, Bahrore, Brahmanabad, Aror, Dipalpur and Multan. By 713 C.E., he established his control in Sind and parts of Punjab up to the borders of Kashmir. A major part of what is now Pakistan came under Muslim control in 713 C.E. and remained so throughout the centuries until some years after the fall of the Mughal Empire in 1857.
Muhammad bin Qasim�s treatment of the Indian population was so just that when he was called back to Baghdad the civilians were greatly disheartened and gave him farewell in tears. There was a Muslim community in Malabar, southwest India as early as 618 C.E. as a result of King Chakrawati Farmas accepting Islam at the hands of Prophet Muhammad (pbuh). The Muslim presence as rulers in India dates from 711 C.E. Since then, different Muslim rulers (Turks of Central Asia, Afghans, and the descendants of the Mongol - the Mughals) entered India, primarily fought their fellow Muslim rulers, and established their rule under various dynastic names. By the eleventh century, the Muslims had established their capital at Delhi, which remained the principal seat of power until the last ruler of Mughal Dynasty, Bahadur Shah Zafar, was deposed in 1857 by the British. A few British visitors were given permission by Akbar to stay in Eastern India more than two centuries before. The British abused that privilege, and within a few decades the British began to collaborate with Rajas and Nawabs in military expeditions against the Mughals and Muslim rulers of the east, southeast and south India. After two centuries of fighting, the British succeeded in abolishing the Mughal rule in 1857.