Introduction:
Al-Hajjajj, the Governor of Iraq, played a significant role in expanding the Arab rule in the Indian subcontinent. He sent several military expeditions to conquer India, and one of the notable commanders he dispatched was Muhammad bin Qasim.

Muhammad bin Qasim:
Muhammad bin Qasim was a young and talented military commander who was appointed by Al-Hajjajj to conquer Sindh, a region in present-day Pakistan. In 712 CE, at the age of 17 or 18, Qasim led an army to invade Sindh.

Reasons for the Invasion:
The invasion of Sindh had both political and economic motivations. The regional power struggles within Sindh provided an opportunity for the Arab forces to intervene and establish their authority. Additionally, the wealth and resources of Sindh, including its prosperous trade routes, were attractive to the Arab rulers.

Conquest of Sindh:
Muhammad bin Qasim's military campaign in Sindh was highly successful. He defeated the local Hindu rulers and consolidated his control over the region. Qasim's army was well-disciplined and organized, which enabled them to overcome the resistance they faced.

Treatment of the Conquered:
Contrary to popular belief, Muhammad bin Qasim did not engage in widespread destruction or persecution of the local population. He implemented a relatively lenient policy towards the conquered people, allowing them to practice their religion and retain their social customs. This approach helped in maintaining stability and minimizing resistance.

Legacy:
Muhammad bin Qasim's conquest of Sindh laid the foundation for the subsequent Muslim invasions in the Indian subcontinent. It opened the door for further Arab and Central Asian invasions and significantly influenced the course of Indian history. The conquest marked the beginning of a long period of Muslim rule in the region.

Conclusion:
Muhammad bin Qasim was sent by Al-Hajjajj, the Governor of Iraq, to conquer India. His successful campaign in Sindh and the subsequent establishment of Arab control paved the way for further Muslim invasions in the Indian subcontinent. Qasim's conquest had a lasting impact on the region's history and marked the beginning of a new era.