Bengal, remote from Delhi, was a land of ravines, rivers and bad roads. Realizing that travel by road was extremely difficult, Sher Shah constructed the Grand Trunk Road from Attock to Delhi, later extending it to Sonargaon (now called Painam) which became its eastern terminus. This highway ran northward by way of modern Narayangunj. From Chah Sarai (Sarai of the well) the road struck due north of Dacca, through the Bhowal Zamindari to Sherpur Atiya. The road ultimately followed the site of the Older road through Garhi to Bihar.
Source:
Farooque, Abdul Khair Muhammad. 1977. Roads and Communications in Mughal India. Delhi: Idarah-i Adabiyat-i, 11.