This was a defining moment in India's environmental movement, and a modern application of the Ghandian principle of satyagraha, or nonviolent resistance, which has characterized many later Indian grassroots movements including, for example, protests over the damming of the Narmada River. It has also launched the careers of high profile Indian environmental activists including Vandana Shiva.
While forests are critical for subsistence (food, fuel, fodder, medicinals, materials) to rural communities everywhere, they are especially so to villagers of mountainous regions like the Himalayas, as forests provide valuable stabilizing services to the soil and water. (One of the slogans of the Chipko movement was in fact: "What do forests bear?/Soil, water and pure air.")
In Uttar Pradesh State, where the Himalayas border Tibet, over the years, the state forestry department had been claiming forested land and leasing it off to commercial loggers; predictably, forest rangers were also parceling off land to contractors in return for bribes.
But the issue was more complex than just big bad loggers and innocent villagers. Although at one time, the communal institutions of villagers fostered careful management of forests, these began to erode after the state took control of forest land. As they felt like forests didn't belong to them, the incentives to protect them vanished, and so overgrazing and overexploitation was creating a tragedy of forest commons as well.
Commercial logging began to be linked to the floods and landslides which were becoming more frequent and severe. In 1970, monsoon rains caused the Alakhganda River to rise some 20 meters, flooding hundreds of square kilometers, sweeping away homes, an entire village, 5 bridges and a bus laden with 30 passengers, and killing almost 200 people. Afterwards the state bore high costs clearing the state's many irrigation canals clogged with silt.