What is the most common language spoken in northeast region?

You'll need to be more specific about which "northeast region" you're referring to. There are many northeast regions in the world, each with its own dominant language.

For example:

* Northeastern United States: English is the most common language.

* Northeast India: Assamese, Bengali, Bodo, and Nepali are some of the most common languages.

* Northeast China: Mandarin Chinese is the dominant language.

* Northeast Brazil: Portuguese is the most common language.

Please tell me which region you're interested in, and I can help you find the most common language spoken there.