The Bengali calendar is loosely tied with the Hindu Vedic solar calendar, based on the Surya Siddhanta. As with many other variants of the Hindu solar calendar, the Bengali calendar commences in mid-April of the Gregorian year. The first day of the Bengali year therefore coincides with the mid-April new year in Mithila, Assam, Burma, Cambodia, Kerala, Manipur, Nepal, Odisha, Sri Lanka, Tamil Nadu and Thailand. [Wiki.]
The wiki also states that
Poila Boishakh coincides with the New Years in many other Southern Asian calendars, including:
Assamese New Year, or Rongali Bihu (India’s Assam state)
Burmese New Year, or Thingyan (Burma)
Khmer New Year, or Chol Chnam Thmey (Cambodia)
Lao New Year, or Songkan / Pi Mai Lao (Laos)
Malayali New Year, or Vishu (India’s Kerala state)
Oriya New Year, or Maha Vishuva Sankranti (India’s Odisha state)
Nepali New Year, or Bikram Samwat / Vaishak Ek (Nepal)
Sinhalese New Year, or Aluth Avurudda (Sri Lanka)
Vishu (India’s Kerala state)
Tamil New Year, or Puthandu (India’s Tamil Nadu state and Sri Lanka)
Thai New Year, or Songkran (Thailand)
Tuluva New Year, or Bisu (India’s Karnataka state)
Maithili New Year, or Jude Shital (Mithila)
Shubho Noboborsho!
Life is a Random Draw 
In the book ‘argumentative Indian’, Amartya Sen has a brilliant chapter on calendars. I will recommend that chapter to the readers of this blog.
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Happy New Year to you. We had the Telugu new year a few days earlier. Fascinating.
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