The only outstanding historical event of the district is the march of Alexander the Great, who retreated in 325 B.C through Lasbela and the Mekran, while a second division of his army passed through the Moola pass. After Alexander’s death the country fell to Seleucus Nicator and later on passed from his descendants to the Graeco-Bactrian kings, who were overthrown by a central Asian power, the Sakas, about 130 B.C. About this time Buddhism, of which many traces are still to be found, flourished in the area. The empire of the Sassanians which followed, expanded slowly towards the east. The areas forming the districts of Chagai, Kharan and north-western parts of Kalat were not conquered till the time of Nausherwan (529-577A.D.).
It is said that a Hindu dynasty, called Sewa, ruled over this part of the country prior to the 7th century. Kalat is still known as Kalat-i-Sewa.
The Arabs had reached the Mekran before 711A.D, when Muhammad Bin Qasim conquered the whole of Sind and Balochistan, including Kachhi, and the whole of Kalat in 712 A.D. The Arabs’ power lasted until the end of the 10th century. Shortly afterwards the country is mentioned as forming part of the empire of the Ghaznavids from whom it passed on to the Ghoris. In 1223 A.D., the eastern part of Baluchistan came within the sphere of the raids of Chengiz khan, when the Mongol expedition penetrated towards the south. Sometime later the country, including the plain of Kachhi, came under the rule of Sultan Altamash of Delhi, but it appears to have reverted soon to the Mongols. In the north, at the end of the 14th century, Pir Muhammad, the grandson of Timur, was engaged in fighting the Afghans of the Sulaiman mountains. During the succeeding century the Balochs extended their power to Kalat, Kachhi and parts of the western Punjab. At the same time the Brahuis had been gradually gaining strength and their little principality at this time extended upto Wadh (Khuzdar). From 1556 to 1595 the country was under the Safavids of Persia. In the time of Akbar, the area upto Kachhi was part of the Mughal Empire and from 1638 A.D, it again remained under the sovereignty of the Safavids until the rise of the Ghilzai power.
Meanwhile the Baloch and Brahui territory (comprising the present district of Kalat) was consolidated into an organized state under the Ahmedzai khans of Kalat. The Mirwaris (from whom the Ahmedzais are descendants) were living in Surab near Kalat and having taken Kalat from the former Hindu rulers of the Sewa dynasty, extended their power thence. They fell for a short time under the power of the Mongols, but later regained and held Kalat, for some generations until the rise of Mir Ahmed, the progenitor of the Ahmedzai family in 1666--70 A.D., who have since held the Khanate of Kalat. During the first part of the 19th century, Nadir Shah made several expeditions to or through north eastern Balochistan. It was at this time that Mir Nasir Khan I (who is the historical hero of the Brahuis and is known as Nasir Khan, the Great ) ascended the throne of Kalat. His rule was vigorous, although his political position was that of the head of a confederacy of chiefs and not that of a sovereign ruler. During the 44 years of his reign (1750--94 ) the Brahvi power reached its zenith. The Khanate extended to the districts of Quetta, Kalat, Harrand and Dajal. Nasir Khan asserted his authority over Panjgur, Kej Kasarkand, Dizak and Kharan. His death was followed by half a century of internal strife, decay and disintegration, during which, however, the Khanate survived together with the nominal sovereignty of the successors of Ahmed Shah Durrani. By then nearly the whole of the area came under the British rule.
The political connection of the British with Kalat commences from the outbreak of the first Afghan War in 1839, when this area was traversed by a British army from Sind and afterwards occupied. In the British attack on Kalat in 1840, Mir Mehrab Khan, the ruler was killed. His son, Mir Nasir Khan II was later raised to the masnad by the tribesmen and regained possession of Kalat. In 1842, consequent upon the British withdrawal from Afghanistan the occupied districts were returned 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 Balochistan whose policy was one of conciliatory intervention, tempered with lucrative employment and light taxation. Shortly afterwards he was able to conclude with Khan Khudadad 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. At the end of the Second Afghan War by the treaty of Gandamak (May, 1879 ),Pishin, Sibi, Harani, and Thal-Chotiali were ceded by Amir Yaqub Khan of Kabul to the British Government. During the succeeding years, expeditions were led against the Lalars of Zhob and Bori and the chiefs of Shirani and those areas were occupied. In 1887, all these areas were declared to be the British territory.
In 1883, the Quetta Niabat (comprising the present Quetta Tehsil ) 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 Sub-Division 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 and there were clashes between them in Warjak and Khudabadan villages. The British authorities intervened and a settlement was effected under which Kharan was recognized as a separate minor state under the direct control of the British Political Agent.
In early 1948, Kalat state formally acceded to Pakistan and became part of the Balochistan State Union. In October 1955 with the unification of the provinces of the Punjab, N.W.F.P., Sind and Balochistan, the State of Kalat, alongwith the other states of the Balochistan States Union were merged into one province while Kalat became a separate district and was placed in the charge of a Deputy Commissione