Which rare Maithili dialect is primarily spoken in Bihar's Kosi, Purnia, and Munger divisions?

Q. Which rare Maithili dialect is primarily spoken in Bihar's Kosi, Purnia, and Munger divisions?
Answer: Thethi
Notes: Thethi, also known as Thēth, Thethiya, or Thati, is a rare Maithili dialect mainly spoken in Bihar's Kosi, Purnia, and Munger divisions. As per the 2011 Indian census, it has about 165,000 speakers. Thethi is part of the Indo-European language family.