Today an ordinary Indian town, Gulbarga once was the capital of the Bahmani sultans.
In 1321 the Delhi sultanate gained control of the Deccan Plateau including the Gulbarga district. As a result of a revolt of officers of the Delhi sultanate the Bahmani sultanate emerged in 1347. But already in 1428 the kingdom broke up into five smaller sultanates, including the Bijapur sultanate led by the Adil Shah dynasty - they all fell to the Mughal empire in 1687.
Therefore in 1428 Gulbarga ceased to be the capital of a sultanate (Gulbarga district fell to the sultanes of Bidar and Bijapur), lost all its importance and fell into neglect.
Most of the ruins of Gulbarga fort date from 14th century Bahmani rule.