Prayagraj, March 6 -- On the streets of Allahabad, now Prayagraj, there is a sure-shot way to tell if pilgrims have recently been in the area. Look for mountains of silver and yellow-green disposable plates, piled with paper cups or plastic tumblers bent out of shape, and a smattering of leftovers from the fixed menu of bhandaras across the city: kachori, pumpkin sabzi, and kheer.

Every few steps, the roads are adorned with snapped (or lost) slippers and shoes, a broken bag strap or two. Look up, and you will spot a riot of yellows and reds in the distance-Kumbh devotees from all over India wearing auspicious colours and walking home with their families, communities, even entire villages in tow. Old-timey megaphones strapped to light pol...