Step 1: Understanding the Concept:
The question asks for the primary reason behind the unique feature of Vijayanagara's urban planning, where extensive agricultural lands were enclosed within the city's massive fortification walls.
Step 2: Detailed Explanation:
The rulers of Vijayanagara built a series of concentric fortification walls that enclosed not only the urban core and the royal center but also vast areas of agricultural land, fields, gardens, and forests. Foreign travelers like the Persian ambassador Abdur Razzaq noted this feature with wonder.
The primary reason for this design was strategic and military. In medieval warfare, sieges were a common tactic where an attacking army would cut off the supply lines of a fortified city. By incorporating a large agricultural belt within the walls, the rulers of Vijayanagara ensured that the city's population and army would have a secure supply of food and water even during a prolonged siege. This made the capital remarkably self-sufficient and difficult to conquer through starvation tactics.
While providing food for the royal family (3) or beautification (2) might have been secondary benefits, the main purpose was the protection of the food supply for the entire city during wartime.
Step 3: Final Answer:
The agricultural tracts were incorporated within the fortified area primarily to protect the food source and ensure the city could withstand long sieges.