The Delhi Sultans' Deccan policy refers to the strategic and administrative approaches adopted by the medieval Delhi Sultanate rulers concerning the Deccan region in South India. This policy evolved over various dynasties and periods, with different rulers implementing distinct strategies based on political, military, and economic considerations.

1. Expansionist Policies:
Several Delhi Sultans pursued expansionist policies in the Deccan to extend their territorial influence. Muhammad bin Tughlaq, the Sultan of Delhi from 1325 to 1351, was particularly known for his ambitious but largely unsuccessful attempts to annex the Deccan. His capital, Daulatabad, was strategically located to control the southern regions. However, the vastness and diverse geography of the Deccan presented significant challenges to effective governance and control.

2. Administrative Reforms:
Muhammad bin Tughlaq's successor, Firuz Shah Tughlaq, adopted a different approach. Rather than aggressive military campaigns, Firuz Shah focused on administrative reforms and conciliatory measures to stabilize the Deccan. He appointed local governors and attempted to integrate local elites into the administrative framework. This policy aimed at fostering a sense of cooperation and loyalty among the Deccan rulers.

3. Bahmani Sultanate and Regional Powers:
The establishment of the Bahmani Sultanate in the Deccan in 1347 marked a significant turning point. The Bahmani rulers, with their capital at Gulbarga, emerged as formidable regional powers. The Delhi Sultans recognized the Bahmanis as independent rulers, and diplomatic ties were established. While occasional conflicts occurred, diplomacy and alliances became integral to the Delhi Sultans' Deccan policy.

4. Vijayanagara Empire:
The rise of the Vijayanagara Empire further influenced the Delhi Sultans' approach to the Deccan. The Bahmani Sultanate and Vijayanagara were engaged in a complex power struggle. Delhi Sultans, at times, formed alliances with either power to maintain a balance of power in the region. The Battle of Talikota in 1565 marked a significant event when the combined Deccan Sultanates defeated Vijayanagara, altering the political dynamics in the Deccan.

5. Decline and Fragmentation:
By the 15th century, the Delhi Sultanate faced internal challenges and external threats, contributing to its decline. The Deccan Sultanates, established as independent entities, gradually asserted autonomy. The Bahmani Sultanate fragmented into smaller states – the Qutb Shahis, Adil Shahis, Imad Shahis, and Barid Shahis – each ruling over specific regions in the Deccan.

6. Impact on Cultural Exchange:
Despite political tensions, the Delhi Sultans' interactions with the Deccan facilitated cultural exchange. Art, architecture, literature, and religious practices influenced each other, contributing to a syncretic cultural milieu. The transfer of administrators, scholars, and artisans between the two regions enriched the composite culture of medieval India.

In summary, the Delhi Sultans' Deccan policy was characterized by a complex interplay of military conquests, administrative reforms, diplomatic engagements, and cultural interactions. The dynamics of this policy evolved in response to changing circumstances, including the rise of regional powers and the emergence of the Vijayanagara Empire. The impact of these interactions not only influenced the political landscape but also contributed to the cultural and historical tapestry of medieval India.