It is the second night, and Rehman is hoping they will soon be inside India, where work is waiting for him. But there is still no news.

It’s almost ten at night. Most townspeople are locked in their homes. After the riots, it is not advisable to move around in the late hours. From the temple lane, Ali chases five big cows down the road. He has a cellphone tied to his waist that rings with a Hindi movie caller tune. He says he is on his way.

As he reaches the main road, three more men are chasing groups of cattle. Some are Hindus, most are Muslims. They crisscross in a well-organised route, jogging continuously to keep the animals on course. All night they will be on the run, to converge at a chosen place by morning.

The Indian border guards are on a vigil.

In the last one week, 12,000 cattle have been seized, but a fresh consignment has arrived from Punjab, and the existing ones must be sold to accommodate the new ones. The two cattle sheds in the town are overflowing. The riverine routes are now in spate; it is not easy to push the cattle across.

This is one of the most densely populated international borders on the planet. In West Bengal, on the Indian side, the density is 903 people per square kilometre, whereas on the Bangladeshi side it is 1,000 people per square kilometre. There are 200 villages in south Bengal alone, located within 150 metres of the international border. More than 80 per cent of enclaves – part of a country surrounded on all sides by another country – in the world are concentrated here, relics of a confused history dating back to Mughal times.

It seems that the issue of enclaves here may now be resolved, at least formally. The Parliament of India passed the 119th amendment to the Indian Constitution on 7 May 2015. Under an agreement with the Government of Bangladesh, which this amendment has ratified, the enclave residents could continue to reside at their present location or move to the country of their choice. Many of the enclaves are near Dhubri where the Brahmaputra curves inside Bangladesh. This stretch is about 20 kilometres long. The entire length of the Dhubri border is 134 kilometres.

The huge population pressure along the porous border here makes it almost impossible to detect infiltrators.

With agents and smugglers aiding them, it makes for an ideal trafficking corridor. There are houses right to the zero line. Wherever there is a village right along the border, the fence is broken wide enough for an army to pass through.

By early morning, around 4,000 cattle are rounded up in a huge field. Every night, more than 20,000 cattle find their way from India to Bangladesh across sixty-eight smuggling corridors in the 4,098-kilometre border. Most of those corridors are here in Assam.

Cellphone messages from either side will determine exactly when these animals will go to the slaughterhouse. But before that, formalities must be completed. A hundred-rupee note for each animal will be forced upon the border guards, and while a group encircles the guards, another group will herd the cattle over the border. They usually generate some chaos by pretending to have a Hindu-Muslim argument and then infiltrate.

In this chaos, Rehman and his family must cross over. This gives the Indian border guards their classic excuse, which they most often cite when questioned: they were surrounded by villagers and attacked with machetes and sticks, and in self-defence they opened fire, killing people. The truth is, whoever pays gets away, and those who don’t are shot. Rehman has made his payment, so he is hoping to get away.

It is near the end of the final journey for the cows.

They’ve travelled a long way from the heart of India. This consignment has come all the way from Madhya Pradesh. The cows come from Punjab, Haryana, Bihar and Madhya Pradesh by the truckload, and each vehicle pays an estimated Rs 20,000 to cross several checkpoints on its way. In the process, at least eight sections of the Indian Penal Code and legislation such as Indian Transport Act and various animal cruelty acts are violated.

Azizur is leading the gang today and will be responsible for the final crossover. Each of the transporters who run through the night will earn only a hundred rupees per cow. Jogamaya ghat in Dhubri is one of the routes that the cattle will take across the border. There are massive boats which come by dawn. The cattle will be loaded on to them.

Some will be made to pass through breaks in the fence. Nightwatchman Ram Narayan Choudhury of Dhubri’s new ghat, one of the exit points, has witnessed this illegal movement every night. Choudhury’s family migrated from Bihar to Assam a hundred years ago.

This trade has been going on for years. It’s done openly, in the presence of police and paramilitary forces. No one says anything. It’s big money. If it’s Rs 5,000 here, it becomes Rs 10,000 there – and those who help in the crossing are paid Rs 1,000. If people like Ram Narayan interfere, they will be killed.

With the break of dawn, more and more cattle make their way towards the river. It’s an unbelievably well-organized mafia that controls this trade. The cows stand in rows of hundreds – big, calm and obedient.

In 1999, the first investigation into this industry was carried out along the West Bengal border. It was reported that more than 15,000 cattle cross over to Bangladesh every night. The volume of trade is a whopping 500 million dollars per annum. It is probably the biggest underworld trade in these parts. The Indian government doesn’t allow the slaughter of cows, except in two states, and neither does it allow the export of cows. So where will all the cows go?

Each cow fetches about Rs 30,000 in Bangladesh, which is one of the major beef-exporting nations. Bangladesh’s economy of leather exports and bone china crockery also relies on smuggled cattle; they are regularised as “animals of unknown origin” once they reach Bangladesh.

There are registered cases of cattle smugglers running FICn (Fake Indian Currency notes) rackets, and it’s not improbable that cattle smuggling is a secondary source of terror-funding in some cases.

Rehman can barely understand the fuss with cows, but he knows that the people who deal with these animals are powerful.

Excerpted with permission from Blood on My Hands: Confessions of Staged Encounters, Kishalay Bhattacharjee, HarperCollins India.