I. Sultani Era:
Bangalah as a territorial name came to be used from the 14th century onwards, more specifically from the time of Sultan Shamsuddin ILIYAS SHAH, denoting the territory which now comprises the modern independent state of Bangladesh and the Indian state of West Bengal. Ziauddin Barani was the first Muslim historian who used the terms iqlim-i-bangalah or diyar-i-bangalah (by which he meant eastern Bengal). Shams-i-Siraj Afif (1357 AD) mentioned Iliyas Shah as 'Shah-i-Bangalah', 'Sultan-i-Bangalah' and 'Shah-i-Bangaliyan' after he had consolidated his power over whole of Bengal by bringing LAKHNAUTI, SATGAON and SONARGAON under his sole control.
II. Mughal regime:
The Mughals after establishing their supremacy over the region included Bangalah as a subah (province) which came to be known as Subah-i-Bangalah. Abul Fazl, the Mughal historian explained the origin of the name thus: The original name of Bangalah was Bang. Its former rulers raised mounds measuring ten yards in height and twenty in breadth throughout the province, which were called ‘al’. From the suffix, this name Bangalah took its rise and currency. One may not agree with the explanation of Abul Fazl, but it is obvious that he meant that 'Bangalah' originated from 'Bang', ie 'Vanga' of the pre-Muslim period.