Across the Himalayan regions of northern India, Nepali migrants build and maintain mountain highways. For the Nepalese, migrating to India does not involve expensive air travel, passports, and visas. There is no official restriction for Nepalese to work in India. The flip side is there is no official body to ensure their well-being. The same can be said for people from Jharkhand and Bihar.
Link : https://www.thequint.com/news/india/himachal-pradesh-migrant-workers-plight-attention-needed