The three authors who wrote about Harshavardhana were: (i) Hieun-T-Sangs (Xuan Zang)  (ii) Banabhatta  (iii) He himself written some books.  

Well-ordered army can be maintained by the rulers.
During this period, a modernized army can be emerged.
An army can be maintained by military commanders and this can be provided to the rulers when they need.
Those military commanders does not get any salary.
They are granted in the forms of lands.
Collection of land revenue is the right given for them.
These revenues are used to maintain the military forces.
According to them, when the king become weaken then the military commander become independent which is

Authors who wrote about Harshavardhana:
- Banabhatta: He was a Sanskrit scholar and a poet in Harshavardhana's court. He wrote the biography of Harshavardhana in his work called "Harshacharita".
- Xuanzang: A Chinese Buddhist monk and traveler who visited India during Harshavardhana's reign. He wrote about the political and social conditions of the time in his travel accounts.
- Hsuan-tsang: Another Chinese traveler who wrote about Harshavardhana's empire and his patronage of Buddhism.

Changes in the army during Harshavardhana's time:
- **Composition**: Harshavardhana's army consisted of cavalry, infantry, and elephants. The cavalry, known as the "Huna", was a significant component of his military force.
- **Armament**: The army was equipped with advanced weapons like swords, bows, arrows, and spears. The use of elephants in battles was also prominent during this period.
- **Organization**: Harshavardhana reorganized the army structure, introducing new tactics and strategies. He focused on training his soldiers and improving their combat skills.
- **Expansion**: Under Harshavardhana's rule, the army expanded its territory through successful military campaigns. The army played a crucial role in maintaining law and order in the empire.

These changes in the army during Harshavardhana's time reflect his efforts to strengthen and modernize the military force to ensure the security and stability of his empire.