The Punjab Unionist Party was formed in 1923 by Fazl-i-Husain and Chhotu Ram, a Muslim Rajput and a Hindu Jat, on an explicitly agrarian and cross-communal basis. It governed Punjab for most of the period from 1923 to 1947.
Its constituency was the landholding peasantry of all three communities against the urban moneylending and commercial classes. Its legislation, the Punjab Relief of Indebtedness Act, the Restitution of Mortgaged Lands Act, was aimed at debt and land alienation.
It was the only successful cross-communal party in any Indian province in the interwar period, and it held Punjab against both the Congress and the Muslim League for two decades.
It collapsed between 1944 and 1946. The League's rise, the death of its leaders, and the intractability of the Pakistan demand pulled its Muslim base away. The coalition ministry under Khizar Hyat Khan Tiwana resigned in March 1947 and Punjab went straight into the violence.
The Unionist experiment is the strongest evidence that the partition of Punjab was not inevitable on communal grounds, and its collapse is the evidence for how quickly that ceased to matter.
It was formed in the 1920s as a coalition of rural landholders across religion, against the urban and professional politics of the Congress and the League.
It governed Punjab from 1923 until 1947 with only short interruptions, which makes it the most durable provincial party of the colonial period anywhere in India.
It was destroyed by the 1946 election, when the League took the Muslim rural vote it had been built on. The province had no cross communal politics left when it needed it most.