The 1920 Congress allied with conservative Muslims to oppose the threatened Islamic Caliphate

Evidence

The third big constituency the Congress party needed to address was the Muslims (who, for caste Hindus, counted on the purity–pollution scale as mleccha—impure; sharing food and water with them was forbidden). In 1920, the Congress decided to ally with conservative Indian Muslims who were leading the pan-Islamist agitation against the partitioning of the Ottoman territories by the Allies after the First World War. The Sultan of the defeated Ottomans was the Caliph, the spiritual head of Sunni Islam. Sunni Muslims equated the partition of the Ottoman Empire with a threat to the Islamic Caliphate itself. Led by Gandhi, the Congress party leapt into the fray and included the Khilafat (Caliphate) agitation in its first national satyagraha. The satyagraha had been planned to protest the Rowlatt Act passed in 1919 to extend the British government’s wartime emergency powers. — Ambedkar, B R, Annihilation of Caste_ The Annotated…, 163