Early interactions between Arab traders and regions of western India were often violent as Muslim invaders spread throughout northern India in the 1000-1500 period. The Sultanate of Delhi established the first Islamic state in northern India with limited influence elsewhere. While the two cultures had significant differences like Hinduism being closed versus the open Muslim community, interactions became less violent over time as the Muslim population increased and mosques were built. Conversions occurred among lower castes, untouchables, and Buddhists, but Hindus did not widely convert. Both cultures influenced each other through adoption of customs and ideas.