Muḥammad Bakhtiyar Khalji was the first Muslim to conquer and rule Bengal.In Bengal, during his establishment, the Islamic missionaries achieved their greatest success in terms of dawah and number of converts to Islam.Bakhtyiar served as a military general of the Delhi Sultanate’s founder Qutb al-Din Aibak. Afghan military chief Bakhtiyar Khilji, destroyed the great universities like Nalanda, Vikramshila and Odantpuri. For a brutal ruler and a strategist like him, his death in 1206 CE was surprisingly tame.
Bakhtiyar Khalji, a member of the Khalaj tribe, a Turkic tribe long settled in what is now southern Afghanistan,was head of the military force that conquered parts of eastern India at the end of the 12th century and at the beginning of the 13th century.
Bakhtiyar Khalji inaugurated Muslim rule in Bengal by conquering Nadia in early 1205 AD. He entreated Muhammad Ghuri at Ghazni to enlist him as a soldier but, because of his short physical stature with long arms extending below the knees, his prayer was rejected. A dejected Bakhtiyar proceeded to Delhi and sought an employment under Qutbuddin but there also his fate fared no better. Hence he went to Badaun where Malik Hizbaruddin appointed him to a lower post.
In 1203 AD Bakhtiyar made a sudden dash against Bihar, occupied it, destroyed Odantapur Bihar. He met Qutbuddin Aibak and gave him valuable gifts. Qutbuddin in turn received him with great honour. Turning now his attention towards Bengal Bakhtiyar started on his adventure in the winter of 1204 AD and, proceeding through the unfrequented Jharkhand region, marched towards Nadia that only eighteen horsemen could keep pace with him. The city dwellers took him to be a horse-dealer and he captured the palace by surprise.
One of the important events in the career of Bakhtiyar Khalji was his Tibet expedition. Bakhtiyar collected necessary information about the routes leading to Tibet by sending there a few detachments. Ali Mech, a Mech trivial, agreed to act as his guide through the hills. Before undertaking his Tibet expedition Bakhtiyar made adequate arrangements for the defense and administration of his kingdom.
Khalji led the expeditionary force of 10,000 horsemen from Gaur and marched northwards along the Brahmaputra River.He went through the territory of Kamarupa in the sub-alpine Himalayan hills, where his army crossed an ancient stone bridge on the Teesta River. Khalji courted the support the king of Kamarupa, who allowed Bengali forces to pass through his territory. The expedition marched through what is today Sikkim and Bhutan and reached the Chumbi Valley in Tibet proper.
In a battle with the local people, he sustained heavy losses and decided to abandon the project. But the backlash was so hard that the return journey proved to be disastrous and he somehow reached Devkot with a little more than a hundred of his followers alive.
Following his catastrophic defeat in Tibet, Bakhtiyar Khilji plunged into a deep depression. It is said that he never left his bed and even his own generals began to turn against him. In August 1206, Ali Mardan Khilji, one of his principal generals, arrived in Devkot and finding him bed ridden, pulled the sheet from his face and stabbed him to death. This is how the brutal ruler met his death.