Having consolidated his position, Firuz Shah turned his attention towards the expansion of his kingdom. The Muslim principality of
Lakhnauti was limited to Bihar, north and northwest Bengal and up to Lakhnur in southwest Bengal.
Rukunuddin Kaikaus had already started the conquest of the eastern part of Bengal, and the task was completed during the time of Firuz Shah. It is said that Kaikaus issued coins for the first time from the Kharaj of Bang. But during the time of Firuz Shah the
Sonargaon area (southeast Bengal) was included in the Muslim Kingdom. He built a mint at Sonargaon from where a large number of coins were issued. Similarly, the conquest of
Satgaon, begun during the time of Kaikaus under his general Zafar Khan, was completed during the time of Firuz Shah. From an inscription of Firuz, it is learnt that one Zafar Khan built a madrasa called
Dar-ul-Khairat in 1313 CE. Very little is known about his conquest of
Mymensingh. It is only known that his son Ghiyasuddin Bahadur issued coins from Ghiyaspur mint, identified with a village having the same name, about 24 km from Mymensingh. During the reign of Firuz Shah, his nephew
Sikandar Khan Ghazi led a fruitful expedition against Matuk, a Hindu Raja of the Sundarban area. A coin of Sultan Firuz has been discovered in a village in the extreme south of
Satkhira District. The most important event of the reign of Firuz Shah was the
Conquest of Sylhet. According to an inscription Firuz Shah conquered Sylhet in 1303 CE. The names of the Sufi-saint
Shah Jalal and the commander
Syed Nasiruddin are associated in connection with the conquest of Sylhet. Firuz Shah held Bihar firmly against the Khaljis. Two inscriptions of his reign, discovered in Bihar, prove this. Thus during his time, Lakhnauti extended from at least the rivers Son and Ghogra in the west to Sylhet in the east and from
Dinajpur-
Rangpur in the north to
Hughli and the
Sundarbans in the south. ==Sharing power==