By Chris Morris BBC News, Delhi

Many marchers are angry at government policies

They have come from all across this vast country, marching in long lines every day for nearly four weeks - some 25,000 tribal people and landless labourers, bringing their battle to the heart of India's capital.

Flags wave and drums are beaten. Everyone has a story to tell.

Either they have lost land to corrupt politicians and new industrial zones, or they have never had any land in the first place, and they struggle to survive.

"The government is giving land to big companies for factories," says Juma Rao, from Gwalior.

"So why can't they give a little bit to us? We're here to claim our rights."

The march is remarkably disciplined - people are divided into groups of 100 for eating, for walking, and for chanting.

Some carry banners, others hold bows and arrows. More than a few look exhausted. All in all, it is an extraordinary sight.

Political process

Ivan Nutbrown is a British charity worker who has helped fund the organisers of this huge event. He says land reform is rural India's most important issue.

"If you don't have land the only source of employment is labouring for other people, and it's a very precarious life.

The marchers plan to stage a mass rally in Delhi on Monday

"Increasingly with India's industrial development, land is being taken, and people are forced to migrate and they add to the sprawl and the pollution of urban India."

So the march has been designed to put pressure on India's political leaders to set up a national authority to oversee land reform and a system of fast track courts to deal with the long delays in resolving land disputes.

The organisers have already met Congress Party President Sonia Gandhi, who they say was sympathetic.

"I'm hopeful that we will achieve something," says Ramesh Sharma, who has been coordinating the political campaign.

"The political reaction has been pretty positive. And now we have a new slogan - if you're not ready to give us land, then give us jail."

And change really is essential.

For all of India's stellar economic data, there are still more people in this country who have to live on less than a dollar a day than in the whole of sub-Saharan Africa.