After the collapse of the Chola Empire in the 1200s AD, their old enemies, the Pandyas, took over control of south India. Both the Cholas and the Pandyas spoke Tamil, and mostly they're the same culture, though different ruling families - both Hindus. Like the Cholas, the Pandyas invaded and controlled the nearby island of Sri Lanka and its pearl and steel industries. The Pandyas were fishing and sailing people, who maintained a big navy. Like the Cholas, they had many trade contacts with Southeast Asia, the Arabian Peninsula, and East Africa. With the north so weak, however, and fewer and fewer Buddhists in India, the old Buddhist university at Nalanda gradually declined as scholars went to the newer, stronger Islamic university in Baghdad.
The first and only really powerful Pandya king was Jatavarman Sundara, in the 1200s, who not only defeated the Cholas but also several other less powerful neighboring kingdoms to unite South India. Jatavarman Sundara probably died about 1268, and his son Maravarman Kulasekara ruled after him. Maravarman died in 1308, and after a short civil war between his sons, Marvarman's son Sundara Pandyan took power. In 1311, one of the northern Indian sultans invaded south India on a looting expedition for plunder, and destroyed several Hindu temples. Sundara tried to counter-attack but his army and strategy were seriously outmatched and he lost and was captured.
In order to get Sundara back, the Pandyas had to give up even more gold and jewels, and a lot of rice, and many elephants and horses. That was the end of the Pandyas.
But by 1325, under the Tughluq Dynasty, the power of northern India began to decline. In the south, people began to feel united by their common enemy and their Hinduism, and by 1336, Harihara I and his brother founded a new South Indian empire, the Vijayanagara Empire.
The next Vijayanagara ruler, Bukka Raya, conquered more land, and so did his son Harihara II. By about 1400, Harihara II controlled all of South India. His grandson Deva Raya II expanded the empire to include overseas land including Sri Lanka and parts of Burma by the mid-1400s.
After Deva Raya II died in 1446, the empire lost ground, only to be pulled back together again by a new dynasty at the very end of the 1400s. When Vasco da Gama first rounded Africa and came into the Indian port of Calicut in 1498, the Vijayanagara Empire was the strongest power in south India.