Taant (তাঁত), and the weavers who came from Dhaka
Shantipur has been known for its handloom for a long time. The town was a centre of Sanskrit learning for centuries and is tied to Advaita Acharya, one of Chaitanya's companions; its weaving gave its name to the Shantipuri saree. After Partition, weavers who left Dhaka settled around the town and in Phulia, its neighbour.
That history explains why Nadia's ODOP entry names three sarees together, Tangail, Jamdani and Shantipore, and why one unit may sell all three. It also explains the chain of buyers in the matrix above. Few weavers sell directly; a unit collects the lot, a mahajan buys it for a city market, and a shop sells it on. WhatsApp sits between every pair.