Bonding over fish:
The fish eating cultures of South and Southeast Asia have a lot in common.
Despite the 'everybody is vegetarian' myth that people somehow believe about South Asia, the fish-eating peoples of coastal India, Bangladesh, through the porous hills of Bangladesh / Myanmar, Thailand, Vietnam, all the way to southeast China, to Indonesia share many things.
For centuries, there was so much trade and sea-faring adventures between these places. While we now think of those locations are completely separate geographic spheres, there were Hakkas in Calcutta and Dhaka, and there were Bengalis in Malaysia, Indonesia and beyond.
Heck, the I-Ching says there were regular ships between the Bay of Bengal and the Srivijayan empire (..700 AD?)