Human–Environment Interactions in a Changing Alluvial Landscape in Ancient Bengal Over the Past Two Millennia: The Site of Mahasthangarh, Bangladesh

Abstract

Mahasthangarh is a fortified city from ancient Bengal, founded around the 4th century BCE and thriving until the 13th–14th centuries CE It is located on the Barind terrace along the Karatoya River, which may appear modest today, but was a major river in the past. Through the first chronostratigraphic records sampled around Mahasthangarh, this paper aims to document human–environment interactions in a changing fluvial landscape linked to the mobility of the Karatoya over the last two millennia. During the first millennium CE, the Karatoya was part of the ancient Tista River. Its flow was stronger, leading to severe flooding that destroyed part of the citadel. Despite this, Mahasthangarh underwent several phases of growth, particularly from the 7th to 10th centuries CE (Pala Period). From the 11th to 13th centuries CE, the river shifted, especially after an earthquake in 1255. This shift was followed by changes in alluvial processes and landscapes in the 13th century CE, likely contributing to the site's decline around the 13th–14th centuries CE The filling and shifting of the Karatoya continued throughout much of the second millennium. It was only at the end of the 18th century CE that the river declined significantly, mainly due to an avulsion of the Tista, leading to its present state.