Muhammad Shah II was succeeded by his two sons, namely Ghiyas-ud-Din and Shams-ud-Din. However, their rule lasted for a few months only. In November, 1397, the throne was captured by Firuz, a grandson of Ala-ud-Din Hasan Bahmani. He took up the title of Taj-ud-Din Firuz Shah.
The author of Burhan-i-Maasir says that Firuz Shah “was an impetuous and a mighty monarch and expended all his ability and energy in eradicating and in destroying tyranny and hearsay and he took much pleasure in the society of the Shaikhs, learned men and hermits.” However, after a few years of rule, he got himself involved into the common vices of his time.
He began to drink hard. He became passionately fond of music. He maintained a large harem which included women of several nationalities. As a Muslim could not have more than four wives, the Sultan resorted to Muta marriages. It is said that about 800 women were daily admitted into his harem in this manner.
In 1389, war broke out with Vijayanagar whose ruler marched into the Raichur Doab with a view to take possession of the fort of Mudgal. Through treachery, the son of the ruler of Vijayanagar was killed. Aggrieved by the death of his son, Deva Raya made feeble resistance and ran away with his army.
A large number of Hindus were slaughtered. Another war with Vijayanagar started in the year 1406. The immediate cause of this war was the desire of the ruler of Vijayanagar to obtain possession of the beautiful daughter of a farmer in Mudgal. The accounts of the beauty of the girl were given by a Brahman who had taught her and the ruler of Vijayanagar decided to marry her.
However, the girl refused the offer on the ground that it would mean her final separation from her own kith and kin whose affection she valued more than the offers of a King. The ruler of Vijayanagar marched his troops towards Mudgal in order to capture her by force. On hearing the approach of the army, the inhabitants ran away including the parents of the girl. As the girl could not be found, the troops plundered the country.
This was too much for Firuz Shah. The war started between Vijayanagar and Bahmani kingdom and ultimately the ruler of Vijayanagar was defeated and he had to agree to give his own daughter in marriage to Firuz Shah and also pay a huge war indemnity. Firuz Shah married his own son Hassan Khan to the daughter of the farmer who was the cause of the whole trouble.
In 1420, there was another was between Vijayanagar and the Bahmani kingdom and it ended in the defeat of the latter. Mir Fazlullah, Commander-in-Chief of the Muslim forces, was killed in the battle-field.
The Sultan himself ran away in utter confusion. The Vijayanagar troops occupied the southern and eastern districts of the Bahmani kingdom. The defeat so much influenced the mind and body of the Sultan that he left his administration in the hands of his two slaves. According to one view, Firuz Shah died a natural death. The other view is that he was forced to abdicate in favour of his brother, Ahmad Shah in 1422.