How was Arunachal Pradesh connected to Assam before 1972?

Before 1972, the region now known as Arunachal Pradesh was administered as the North East Frontier Agency (NEFA) and functioned as a part of the Indian state of Assam.123

During the British colonial era, the area was organized into various frontier tracts, such as the Balipara and Sadiya frontier tracts, which were later consolidated into the NEFA. Following India's independence in 1947, the region remained integrated within Assam until it was separated and elevated to the status of a union territory in 1972. It eventually achieved full statehood in 1987.412