Iltumish (Shams ud-din Iltutmish), the third Sultan of Delhi (1211-1236), introduced the Iqtadari system - a land revenue system where land was assigned to officials (iqtadars) in lieu of salary. Akbar later refined it as the Mansabdari system, and Ala-ud-din Khilji had his own revenue reforms. Muhammad bin Tughlaq's experiments were different.