The Mahasthabir Nikaya or Mahāsthabir Nikāya is a Bengali order of Buddhist monks.
They were anti-reformists and anti-foreign influence who attempted to replace the movement led by Saramitra Mahasthabir ("Saramedha Mahathera" in Pali), which led to the formation of the Sangharaj Nikaya in 1864.
The anti-reformation movement came into being in order to counter-act that which was led by Saramitra Mahasthabir.
The Mahasthabir Nikaya believed that a Bengali Buddhist order should not come under a powerful influence from a foreign entity.
The distinction served only to maintain an organizational front, not a doctrinal opposition.