How was Sindh conquered?

Sindh was conquered by the Arab armies of Muhamad Bin Qasim, a general who served under the Umayyad caliphate.

Invading the region in 712 AD, the Arab armies defeated an army led by Raja Dahir. This event would lead to beginning of Muslim presence in North India.

For further reading check the following articles:

• Arab and Turkish Invasions
• First Battle of Tarain of 1191
• Second Battle of Tarain of 1192