Analysis of information sources in references of the Wikipedia article "History of Bengal" in English language version.
In C1020 ... launched Rajendra's great northern escapade ... peoples he defeated have been tentatively identified ... 'Vangala-desa where the rain water never stopped' sounds like a fair description of Bengal in the monsoon.
A passage of Pliny clearly suggests that the "Palibothri," i.e., the rulers of Pataliputra, dominated the whole tract along the Ganges. That the Magadhan kings retained their hold on Bengal as late as the time of Aśoka is suggested by the testimony of the Divyavadāna and of Hiuen Tsang who saw Stupas of that monarch near Tamralipti and Karnasuvarna (in West Bengal), in Samataṭa (East Bengal) as well as in Pundravardhana (North Bengal).
A large number of monasteries had been established in different parts of Bengal (Samatata, Pundravardhana, Tamralipta etc.) during the time of Asoka. This is known from Hiuen Tasng who had seen them when he visited Bengal... In Asoka's time Tamralipta was the chief port of the Magadhan empire and the communication between Ceylon and Magadha was maintained through Tamralipta. Asoka paid his visit to Bengal and at least once he came to Tamralipta. From the Ceylonese chronicle, the Mahavamsa, we come to know how Asoka visited Tamralipta on the occasion of the voyage of Mahendra and Sanghamitra with the holy branch of the Bodhi tree to Sinhala (modern Srilanka) at the time of the rule of the pious king Devanampriya Tissa of Ceylon .
In 1346 ... what became known as the Bengal Sultanate began and continued for almost two centuries.
The rulers of the Sultanate Bengal are often blamed for promoting Islam as state sponsored religion.
[Rājendra Chola I], after conquering eastern Bengal (Vangāladesa),
[Rājendra Chola I], after conquering eastern Bengal (Vangāladesa),