Most people in ancient Indian were farmers but since India is between China and West Asia and Europe trade was very good. Indian people were selling West Asian things like gold to people in China, and Chinese things like silk and pottery to people in West Asia. They would also sell them Indian things like spices, and cotton cloth. With all this trade India became a very rich country. Then trade started to change in Indian because people began to trade using ships on the ocean, which could carry more stuff more easily and safely than donkeys or camels could on land.
Religion has almost always remained the same throughout Indian history. It was always a central 4 which is Jainism, Buddhism, Hinduism, and Islam. Buddhism began in India and spread to other places in Asia. Islam came into India from West Asia. The history of Hinduism is unclear. Jainism also started in India. These core religions have change over the years. Islam, Christianity, Sikhism, Buddhism and Jainism are now the lead religions in India.
The ancient Indian people has a caste system goes like this Brahmin (Priest), Chetri Kshatriya, (Ruler & Warrior) Vaishya, (Merchant, Trader, and Artisan) Shudra, (Farmer and Laborer) and Untouchables. This caste system has been used throughout their whole history and will never change. With such a consistent system that is why they have last as long as they did.