Tibetans from the high plateaux of the north-east settled in the Indus Valley around 500-600 BC. At that time they followed the Bon religion. In the 7th century Buddhism was brought to this region of Ladakh by the great Lama Songsten Gampo. Its influence soon spread south across Zanskar towards the Kashmir valleys.
Due to the isolation of Zanskar the area has remained devoutly Buddhist to this day, whereas the more accessible Kashmir was later converted to Islam. After a period of relative independence, with periodic internal conflicts, Zanskar was finally annexed by Ladakh in the 17th century. The kings of Ladakh and of Zanskar belonged to the same family, which ensured a period of peace. From 1842 onwards Ladakh and Zanskar are part of the state of Jammu and Kashmir, the only Indian state to extend to both sides of the Himalaya. This situation was unaffected by Indian independence in 1947.
While Leh is the capital of the District of Ladakh, Padum (the main settlement of Zanskar) chose to be attached administratively to the Muslim town of Kargil, situated on the main highway from the valley of Kashmir up to Leh. Kargil was, and still is, the origin of the only road link to Zanskar, providing a break from its isolation from May to November each year.
Since October 31st 2019, the state of Jammu and Cachemire has been divided in two union territories : the union territory of Jammu and Kashmir and the union territory of Ladakh. Zanskar is still a part of Kargil district but this one depends on the union territory of Ladakh.