The earliest Vedic literature comes from a background of pastoralism giving way gradually to agricultural settlements. Early Buddhist literature suggests a more settled agrarian economy and an emergent commercial urban economy. The post-Maurya period witnessed a series of small kingdoms ruling in various parts of the subcontinent and at the same time a tremendous expansion in both internal and external trade. The Gupta and Post Gupta periods witnessed the beginning of a major change in the agrarian system with the assignment of land grants and revenue grants and revenue grants to both religious and secular assignees resulting in a new politico-economic structure in many parts of the subcontinent. The migration of the Aryan speaking peoples brought in the new Aryan elite.
Though the brief campaign of Alexander did not seriously disturb the centres of powers in the Punjab and Sind, the invasions of the Indo-greeks, Sakas and Kushanas for two centuries definitely affected Indian society in the northern and western parts of the subcontinent. The impact of the Huna invasion in the 5th century AD was felt as far as the heartland of the Ganges. The migrations of people from central Asia to northern and western India in the post-Gupta period produced an even greater impact.