The first British diplomatic contact with Baluchistan was when Britain became engaged in the disastrous FIrst Afghan War in 1839. A precondition for the invasion of Afghanistan was the safe passage of British troops in the lands of the Baluchis. Alexander Burnes arrived in Kalat to negotiate these terms. The Khan (Mehrab) agreed in principal but as long as the British agreed to leave the Khanate after the Afghanistan expedition had been completed and also if the British helped restore Baluchi control over Karachi. The British were reluctant to agree and even put forward the condition that the Baluchi Khan recognise the overlordship of Shah Shujah who they were trying to back in Afghanistan. As the negotiations protracted, British patience finally snapped and an invasion and occupation of Kalat was ordered.
The Invasion started on November 15th, 1839. It resulted in the bombardment of the Kalat Palace and the death of some 300 people. Mehrab Khan was killed and a successor was appointed; Shah Nawaz Khan. The British intended to keep some control over his rule by appointing a certain Lieutenant Loveday as the Khan's political officer. However, this lack of political independence helped usher in a rebellion from the Sarawan tribes. Shah Nawaz was forced to abdicate to Mir Nazir Khan II.
The unfolding disaster in Afghanistan meant that there was little political or military interest in remaining in the area and the British were ultimately happy to return control of the Khanate to the Khan of Kalat. The British negotiated with the Kalat State in 1854 and according to the terms of the treaty, British political agents were deputed to Kalat during the next twenty years.
In 1874 Sir Robert Sandeman was sent to Baluchistan whose policy was one of conciliatory intervention, tempered with lucrative employment and light taxation. Shortly afterwards he was able to conclude with Khan Khudardad Khan of Kalat the treaty of 1876, which brought Kalat under the British sovereignty and provided stronger political control. To consolidate the territorial extension already made, Baluchistan was made a separate agency under an agent to the Governor General. This was just prior to the launch the
Second Afghan War.
By ther terms of the Treaty of Gandamak in 1879: Oishin, Sibi, Harani and Thal-Chotiali were ceded by Amir Yaqub Khan of Kabul to the British Government. During the next decade, expeditions were led against the Lalars of Zhob and Bori and the chiefs of Sirhani and those areas were occupied. In 1887, all these areas were declared to be British territory. In 1883, the Quetta Niabatand and the Bolan Pass were permanently taken on lease by the British from Kalat State. In 1899, Nushki and in 1903, the area irrigated by the Sind canals, known as the Nasirabad Subdivision was similarly acquired from the Kalat State on a perpetual lease. In 1940, the relation between the Kalat Khanate and the Chiefdom of Kharan became strained there were clashes between them in Warjak and Khudabadam villages. The British authorities intervened and the settlement was agreed under which Kharan, Makran and Lasbela were recognized as a separate minor states under the direct control of the British Political Agent.
In 1948, Kalat State formally acceded to Pakistan and became part of the Baluchistan States Union. Two days before Pakistan declaration of statehood, the Khan (Beglar Begi Mir Sir Ahmad Yar Khan) declared the independence of Kalat, but offered to negotiate a special relationship with Pakistan. Other Baluchi chiefs (sardars) also expressed their preference for a separate identity. Pakistan took military action against them and the Khan, and brought about their accession by force.