Relations with Bhutan
Bhutan is a large hilly country to the East of Sikkim and at India's northern border (as shown in the map given below – highlighted with red line).
Warren Hastings established friendly relations with the ruler of Bhutan after 1774 when Bhutan permitted Bengal to trade with Tibet through its territory.
Relations between the Government of India and Bhutan became unsatisfactory after 1815. The British now began to cast greedy eyes upon the narrow strip or territory of about 1,000 square miles at the base of Bhutan hills containing a number of duars or passes.
This area would give India a well-defined and defendable border and useful tea-lands to the British planters.
In 1841, Lord Auckland annexed the Assam duars.
The relations between India and Bhutan were further strained by the intermittent raids made by the Bhutiyas (tribal group) on the Bengal side of the border.
In 1865, a brief war broke out between the British and Bhutan. The fighting was utterly one-sided and was settled by a treaty signed in November 1865.