[1] The origins of most of the Brahmins in Southern Bengal can be traced back to the Gangetic plains of Northern India, from the ancient city of Kanyakubja (Kannauj).
It is believed that in the 11th century CE, the ruler of Bengal, Adisara, summoned five Brahmins from Kanyakubja, who were known for their superior rank to the region.
These Vedic Brahmins were supposed to have nine gunas (favoured attributes), among which was insistence on same rank marriages.
[2] Though the first wave of Brahmin migration to Bengal started during the Maurya period and the Jain Acharya Bhadrabahu – regarded to be the preceptor of Chandragupta Maurya – is said to have been born in Brahmin family of Pundravardhana (or Puṇḍra), the medium to large scale migrations of Brahmins from other parts of India to Bengal, especially from the ancient Kanyakubja region, happened during the last part of the Buddhist Pala Empire and early part of Hindu Sena dynasty.
For several decades from the 1970s to the 1990s, the West Bengal Higher Secondary board mandatorily changed all spelling variants (Mukherjee, Mukerjee, Mookerjea, Mookerji etc.)