Because of extensive trade, the culture of India became the dominant culture around the Bay of Bengal, profoundly and deeply influencing the cultures of Burma, Cambodia, and Sri Lanka. In many ways, the period during and following the Gupta dynasty was the period of "Greater India", a period of cultural activity in India and surrounding countries building on the base of Indian culture. This medieval flowering of Indian culture would radically change course in the Indian Middle Ages. From the north came Muslim conquerors out of Afghanistan, and the age of Muslim rule began in 1100.