Bakhtiyar Khalji's Tibet campaign

Bakhtiyar Khalji, the general of Qutubuddin Aibak, launched a campaign to invade Tibet in the 13th century.

He was motivated by a desire to control the lucrative trade between Tibet and India. Tibet was a source of the most prized possession of any army, horses, and Khalji was keen to secure this route and control the trade by conquering Tibet. Musalman army commenced plundering the country around the Tibet Region. The people of that fort and town and the parts adjacent advanced to repel the Muslim army, and they came to a battled From daybreak to the time of evening prayer a fierce encounter was carried on, and a great number of the Musalman army were killed and wounded.

Background
Bakhtiyar Khalji, the general of Qutubuddin Aibak, conquered Bihar and Nadia, the capital of the Sena Kings of Bengal. He subsequently became obsessed with ambitions of conquering Tibet. Historically, Bengal had trade relations with Tibet along the 'Tea-Horse Route', through Assam, Sikkim and Bhutan, to parts of China and Southeast Asia, which were home to gold and silver mines. Tibet was also a source of horses. The planned invasion also coincided with the Era of Fragmentation and the collapse of the Tibetan Empire.

The expedition was aided by Ali Mech, a tribal chief, in the foothills of the Himalayas in the north of Bengal. He was a recent convert to Islam, and he helped the expedition by acting as a guide for them.

Campaign
On his way north, he invited the Rai of Kamrud (Kamrup) to join him but the latter refused. After marching for 15 days through the Teesta river in North Bengal and Sikkim, Khalji's army reached the Chumbi valley in Tibet on the 16th day and started looting Tibetan villages. The rugged Himalayan mountain passes were an unfamiliar terrain to the invading army, who were more used to the sultry and humid plains of Bengal. The Tibetans had lured Khalji and his army into a trap and inflicted heavy casualties on the Turkish army and Khalji decided to retreat. But, all along the escape route, the Tibetans continued to carry out relentless guerrilla-style attacks on the retreating army. Khalji's men were so badly defeated that the starving soldiers were forced to eat their own horses to stay alive.

On their way back to Bengal, the army passed through the plains of Kamrup while going through the territory of Kamrup in the sub-alpine Himalayan hills, where his army crossed the ancient stone bridge on the foothills near the Teesta river. The forces found the arches in the bridge to be destroyed by the Kamrup forces which made it difficult to cross the deep river. In a desperate attempt to reach the other side of the river at Devkot, Khalji's forces lost a number of men and horses. It is said that of the 10,000-strong army that had marched into Tibet, only around 100 men returned. After crossing the river, Ali Mech guided Bhaktiyar Khilji back to Devkot (present-day Dakshin Dinajpur district, West Bengal).

Aftermath
There are two accounts of what happened to Bakhtiyar Khalji following the Tibet and Kamrup debacle. One account speaks of him dying from ill health and injury during this retreat to Bengal. Another account notes that he was assassinated by Ali Mardan Khalji after returning to Devkot in Bengal.