During the Sultanate period, the Indo-Islamic culture was best represented by the aspect of architecture. This was a period of significant changes in the architectural style of India, as the Muslim rulers brought in their own architectural styles and techniques, which blended with the existing Indian styles to create a unique Indo-Islamic style.

Some of the key features of Indo-Islamic architecture during the Sultanate period include:

1. Islamic Elements: The most prominent feature of Indo-Islamic architecture was the incorporation of Islamic elements like arches, domes, minarets, and calligraphy.

2. Use of Local Materials: The Muslim rulers also made use of local materials like red sandstone and marble, which were easily available in India, to create their structures.

3. Syncretism: Another key feature of Indo-Islamic architecture was the syncretism of Indian and Islamic styles. For example, the use of Hindu-style brackets to support Islamic arches, or the incorporation of Indian motifs and designs in Islamic structures.

4. Mosques: Mosques were the most common type of structure built during the Sultanate period. Some of the most famous mosques from this period include the Quwwat-ul-Islam Mosque and the Jama Masjid in Delhi.

5. Tombs: Another popular type of structure built during this period were tombs, which were often built to honor Sufi saints. The most famous example of a tomb from this period is the Qutub Minar in Delhi.

Overall, the architecture of the Sultanate period represents a unique blend of Indian and Islamic styles that has had a lasting impact on Indian architecture.