Who created the department of Diwan-i-Arz in Delhi Sultanate, India?

Question

The iron pillar of Delhi, India, a 7.21 m (23.7 ft) high pillar that is 98% pure wrought iron, has withstood corrosion in the open air for how long?

Answer 1

Ghiyas-ud-din Balban
Diwan-i-arz was the Department of Military started by the Ghiyas-ud-din Balban. Following is the list of the department of Delhi Sultanate.

Diwan-i-Risalat     Department of appeals
Diwan-i-arz         Department of Military
Diwan-i-Bandagan    Department of slaves
Diwan-i-Qaza-i-Mamalik  Department of justice
Diwan-i-Ishtiaq     Department of pensions
Diwan-i-Mustakhraj  Department of arrears
Diwan-i-Khairat     Department of charity
Diwan-i-kohi        Department of agriculture
Diwan-i-insha       Department of correspondence