The northern section of India became chaotic as local states tried for power and territory. The Nomadic Turkish-speaking people took advantage of this and went into India and became a part of their society. This arrival though caused more harm than good and just added to the disruption. Even though the Gupta dynasty collapsed there was still some centralized rule. For example in the first half of the 7th century King Harsha temporarily unified northern India with a huge army. Harsha was known for piety, liberality, and scholarship. He was kind to all faiths, built hospitals, provided free medical care to all his subjects, distributed wealth to everyone, and encouraged scholars.
Local rulers though had too strong of a hold despite what Harsha did and Harsha was killed. He left no successor so the local rulers took over once again.

Islamic rule also came in. The military came in the mid-7th century and they were mainly at first there for exploring than conquest. In 711, the Islamic rule conquered Sind (Indus River valley in northwestern India) and went into the hands of the Abbasid caliphs. Sind was at the very edge of the rule so much of population kept their old religion. Local political elites still had some control over the people. The region though still was controlled by the caliphs until the collapse of the Abbasid dynasty in 1258. Muslim merchants spread their faith to coastal regions in all of India. These merchants created small communities and played a huge role in business and trade. They became a part of the Indian society. The invasions and migrations of Turkish-speaking people into India also allowed for Islam to spread. In the 10th century, Turkish groups converted to Islam and some of these Islamic Turkish people went into India when the northern section was very politically unstable. Mahmud of Ghazni (leader of Turks in Afghanistan) mounted 17 raiding expeditions into India and annexed several states in northern India. He was more interested in taking the wealth stored in the temples in India. They tore down many sites that weren't of the Islamic faith and created many mosques and Islamic shrines in their place. These raids though didn't cause many Indians to become Muslims. Mahmud's successors created a systematic campaign that conquered most of the Hindu kingdoms in northern India and established the sultanate of Delhi (Islamic state). The capital was at Delhi and they ruled for 3+ centuries.
In the 14th century, Delhi was considered one of the most powerful in the Islamic world but the authority of the sultans (rulers) didn't extend far beyond Delhi. They made raids to southern India but never could establish control there. In northern India, they had Islamic rule over a group of mainly humans and they depended on Hindu kings to carry out their policies and to advance their interests in local regions. They created a secure place for their faith to spread in India.

Southern India escaped the invasions, wars, and turmoil that the north had even though the south was still politically divided. Southern Indian Hindu rulers ruled small, loosely governed states that rarely competed. The Chola kingdom ruled the Coromandel coast and had a considerably large navy that dominated the waters from the South China Sea to the Arabian Sea. When they were in their height in the 11th century, they captured Ceylon and portions of southeast Asia. Chola rulers gave local and village rulers considerable self governing rights as long as they maintained order and delivered taxes on time. during the 12th century there were revolts in southern India and the people of Ceylon threw the Chola rule out. The Chola realm didn't collapse but it did decrease down to the size and power influence of the other kingdoms in southern India. The southern kingdom called Vijayanagar owed its origin to the sultans of Delhi efforts to control southern India. The forces of explorers created a defensive response in the south. Officials in Delhi sent brothers Harihara and Bukka to take control of the south in Delhi's name. These brothers recognized the opportunity to establish themselves as independent rulers so they returned to their original faith and proclaimed the establishment of Vijayanagar. This establishment didn't cause hatred between Muslims and Hindus. In 1565, Vijayanagar fell to Mughal conquerors. States like the sultanate of Delhi and the kingdoms of Chola and Vijayanagar weren't powerful enough to bring together India but still India had a interesting and distinct society due to the basis of trade, common social structures, and inherited cultural traditions.