Anti-colonial politics in this valley were plains Bengali politics, organised from Sylhet and Silchar rather than from Guwahati, and the question that ran through all of them was administrative before it was national — whether this plain belonged with Bengal, with Assam, or with the country downstream. There was no princely court here after 1832 and no armed rising against the British after the annexation. What there was instead was a tea labour force whose one great collective act, the Chargola exodus of May 1921, is remembered by the act rather than by any leader's name; a Congress and Khilafat organisation that took hold in the towns in the 1920s and only thinly in the countryside; and, at the very end, a referendum that decided the plain's future by counting it.
Non-cooperation and Khilafat in the plain1920–1922
The valley's first mass political campaign. Congress and Khilafat committees were organised across Cachar, Karimganj and Hailakandi, courts and schools were boycotted, and the agitation reached the tea gardens — which is the immediate context of the Chargola walkout.
Outcome: Congress organisation was established in all three subdivisions and survived the collapse of the campaign in 1922; several of the valley's later political figures entered public life through it.
The Chargola exodusMay 1921
Tea labourers walked off the gardens of the Chargola and Longai valleys in the border belt and set out for home, invoking the non-cooperation agitation. Estimates of the numbers involved vary widely between sources. Those who reached Chandpur on the Meghna were stopped at the steamer station on 20 May 1921 and cleared from it by troops.
Outcome: Railway and steamer workers in Assam and eastern Bengal struck in response. The gardens recovered their labour supply within a few years and no legislation followed, but the exodus remains the largest single labour action in the region's history and is observed in the valley as Muluk Cholo Dibas.
The Sylhet referendum6–7 July 1947
A referendum was held across Sylhet district to decide whether it would join East Bengal or remain in Assam. Congress workers from the Cachar and Karimganj belt campaigned for the second option; the majority voted for the first.
Outcome: The Radcliffe Commission subsequently awarded the Karimganj subdivision to India. The plain was divided at the Kushiyara, and the direction the valley's rivers, language and trade had always run became an international border.