What is the link language of the region mentioned in the passage?

Assamese is the most widely spoken language in the state of Assam. It also serves the purpose of a link language throughout the region. As a language it is believed to have evolved from Magadhi, a form of the ancient Prakrit language. However, due to various influences over the years, the language has acquired some variations in its sentence forms. These are called groups of Assamese dialects. Out of these, the dialect of the eastern group is mainly spoken in the Sibsagar district and its surrounding areas. Similarly, the dialect of the central group is mostly spoken in the Nagaon district and its surrounding areas. On the other hand, there are two distinct groups of dialects in the west. These are the Goalparia and Kamrupi groups. Bodo, or Boro, is a major language spoken in the state. It belongs to the Tibeto-Burman language family and is mostly found in the areas falling under the Bodoland Territorial Council. It is the official language there. By the 92nd Amendment of the Constitution of India in 2003, Bodo became one of the 22 scheduled languages of the country.