Why do Naga tribes have many different dialects?

The Naga tribes of Nagaland comprise more than 20 distinct tribes and numerous subtribes, each maintaining a high degree of geographic and social isolation. This historical separation has prevented the development of a common language, resulting in approximately 60 distinct dialects within the Sino-Tibetan language family.12

In many parts of the region, this linguistic fragmentation is so pronounced that dialects can vary significantly from one village to the next. Because of this diversity, the Naga people traditionally rely on broken Assamese—often referred to as Nagamese—as a lingua franca for intertribal communication, alongside the use of English and Hindi.12