Firuz Shah died in September 1388 A.D. He was succeeded by his grandson, Tughluq Shah, son of his eldest son Fateh Khan who assumed the title of Ghiyas-ud-din Tughluq. An effort was made to capture the throne by prince Muhammad, the third son of Firuz Shah but it failed.
However, Ghiyas-ud-din engaged himself in physical pleasures and proved himself completely incapable. It dissatisfied the nobles. Abu Bakr, son of Firuz’s second son, Zafar Khan took advantage of it, conspired against the Sultan and succeeded in dethroning him with the help of dissatisfied nobles in February 1389 A.D. But he too was challenged by prince Muhammad who declared himself Sultan at Samana and with the support of some powerful nobles attacked Delhi.
The nobles at the court and the provincial governors openly supported the cause of one or the other prince. Finally, prince Muhammad succeeded, captured Delhi in August 1390 A.D. and assumed the title of Nasir-ud-din Muhammad Shah. But Muhammad too could not rule for long.
He lost his health due to excessive indulgence and died in January 1394 A.D. He was succeeded by his son Humayun, titled as Ala-ud-din Sikandar Shah. He too died after six weeks and was succeeded by his younger brother Nasir-ud-din Mahmud Shah who was destined to be the last ruler of his dynasty.
The rulers who followed Firuz Shah were completely incompetent. Besides, the throne was hotly contested by many princes of the family and the nobles and provincial governors freely participated in the question of succession. It reduced the honour of the Sultan and also led to disintegration of the empire.
By the time Mahmud Shah ascended the throne, the Delhi Sultanate had lost practically all its distant provinces, viz., the entire south India, Khandesh, Bengal, Gujarat, Malwa, Rajasthan and Bundelkhand. Mahmud Shah also failed to check further loss to the empire. During his reign, Jaunpur and Panjab became independent and he himself was challenged by Nasrat Shah, another son of Firuz at Delhi itself.
It resulted in bifurcation of the reduced kingdom of Delhi itself as none could succeed in finishing his rival. Mahmud Shah ruled at Delhi and Nasrat Shah ruled at Firozabad. The nobles at Delhi joined one camp or the other and frequently changed sides as well. Virtually, there existed no Tughluq empire.
In these very conditions, Timur attacked India. When Timur attacked Delhi, both the rulers fled away leaving their capitals and their subjects to their fate. However, when Timur returned, Mahmud Shah succeeded in capturing Delhi again with the help of his vazir Mallu Iqbal. But he became a puppet in the hands of Mallu Iqbal and once fled away to Kannauj to save his life. But when Mallu Iqbal died fighting against Khizr Khan, he returned to Delhi.
This time, he handed over the reigns of the government to an Afghan noble, Daulat Khan. Mahmud Shah, finally died in 1412 A.D. That finished the rule of Tughluq dynasty. In 1413 A.D., the nobles elected Daulat Khan as the Sultan of Delhi. He, however, was defeated by Khizr Khan and imprisoned. Khizr Khan who now became the Sultan at Delhi laid down the foundation of the rule of a new dynasty viz., the Sayyid dynasty in 1414 A.D.