History of India . An overview : The people of India have had a continuous civilization since 2500 B.C., when the inhabitants of the Indus River valley developed an urban culture based on commerce and sustained by agricultural trade. This civilization declined around 1500 B.C., probably due to ecological changes.

During the second millennium B.C., pastoral, Aryan-speaking tribes migrated from the northwest into the subcontinent. As they settled in the middle Ganges River valley, they adapted to antecedent cultures.

The political map of ancient and medieval India was made up of myriad kingdoms with fluctuating boundaries. In the 4th and 5th centuries A.D., northern India was unified under the Gupta Dynasty. During this period, known as India's Golden Age, Hindu culture and political administration reached new heights.

Islam spread across the Indian subcontinent over a period of 500 years. In the 10th and 11th centuries, Turks and Afghans invaded India and established sultanates in Delhi. In the early 16th century, descendants of Genghis Khan swept across the Khyber Pass and established the Mughal (Mogul) Dynasty, which lasted for 200 years. From the 11th to the 15th centuries, southern India was dominated by Hindu Chola and Vijayanagar Dynasties. During this time, the two systems--the prevailing Hindu and Muslim--mingled, leaving lasting cultural influences on each other.