Being a distant province, Bengal had always been a problematic area for the
Delhi Sultans and could become independent from time to time. Bakhtiyar
Khalji, one of the military commanders of Muhammad of Ghur, was the first
Muslim invader who annexed Bihar and Bengal by overthrowing the Sena
dynasty which however continued to rule for some more time in east Bengal.
Though he probably did not assume the title of Sultan, he had prayers read
and coins struck in his own name. His assassination in 1206 by Ali Mardan
Khalji led to civil war among the Khalji chiefs in Bengal. Ghiyas-ud-din lwaz
Khalji (1213–27), however, restored peace and transferred the capital from
Devkot to the historic city of Laknauti (Gaur). He even assumed the title of
Sultan as an open challenge to Delhi and strengthened his position by
securing investiture from the Abbasid Caliph of Egypt, AI-Nasir. This led to
an invasion of Bengal by Iltutmish which resulted in Ghiyas-ud-din’s defeat.
     During the next 60 years (1227–87), Bengal was ruled by no less than
fifteen chiefs, and of them ten were Mamluks sent from Delhi. Mughis-ud-
din Tughril (1268–81), the last and the greatest of these Mamluks, claimed
independence and thereby provoked Balban, who sent two expeditions.
Though the first expedition failed, the second (led personally by Balban)
succeeded and Bengal was handed over to Balban’s youngest son, Bughra
Khan. Bughra ruled Bengal as governor during the remaining years of
Balban’s reign (1281–87). On Balban’s death in 1287, Bughra assumed
complete independence and took the title of Nasir-ud-din Muhammad.
Bughra’s elder brother, Kaiqubad, who succeeded Balban to the throne of
Delhi, recognised Bughra’s independence. This house of Balban (Bughra and
his successors) ruled Bengal independently till 1328. Ghiyas-ud-din Tughluq
led an expedition to Bengal and restored the suzerainty of Delhi in 1328. But
about a decade later (1339) Bengal again became independent when Fakhr-
ud-din defied Muhammad bin Tughluq and assumed the title of Fakhr-ud-din
Mubarak Shah.
     The history of Bengal entered a new phase when Shams-ud-din founded a
new dynasty, the Ilyas Shahi dynasty, which ruled Bengal up to 1538 with a
few breaks in between. Shams-ud-din Ilyas Shah (1345–58) brought the
whole of Bengal under one unified rule. Besides, he made incursions into
Nepal and Orissa. Even Firoz Shah Tughluq had no alternative but to make
peace with him. His reign was marked by the development of an impressive