And they set a new Guinness reforestation record - earlier record was held by Uttar Pradesh, which planted nearly 50 million trees in a span of 24 hours in July last year.
The state chief minister, Shivraj Singh Chouhan tweeted: "I am extremely proud to happily share that people of Madhya Pradesh successfully planted 6.63 Crore saplings today."
According to press release, the event took place in Central Indian state of Madhya Pradesh with over 1.5 million people planted a total of 66,750,000 tree saplings in no more than 12 hours. The saplings reportedly included two-dozen varieties of plants obtained from different nurseries around the state.
The event, of course, was not all about setting a new record. Its aim was to raise awareness of "the government's colossal nation-wide plan to make India green again." As per agreement from the Paris Climate Change Conference, India's government is investing $6.2 billion to increase forest cover to 95 million hectares (235 million acres) by year 2030.
Large-scale forestation is also taking place elsewhere in India, for example in Kerala (over 10 million trees planted in 24 hours) and Maharashtra (planning to plant 40 million trees by the end of the year).