This is part of my "General Education in a Nutshell" series. The series consists of ten subjects you might study in a general education or "liberal arts" core at a university or college. The first topic in the overall series was philosophy. So far in the world history section:
- World History Overview
- From 9-11 to the Present
- From the Cold War to the Millennium
- From Waterloo to World War II
- 5a. The French Revolution
- 5b. The Enlightenment to the American Revolution
- 5c. From Cromwell to the First Industrial Revolution
- 6a. Reformation and Scientific Revolution
- 6b. The Renaissance and a New World
- 7a. Church Schisms in the Middle Ages
- 7b. Kings Rising in the Middle Ages
- 7c. Medieval Arabia, India, China, and South America
- 8a. The Roman Empire
- 8b. The Roman Republic
- 9a. Greeks and the Hellenistic Age
- 9b. Assyrians, Babylonians, Persians
1. I have read that the most ancient civilization in India was the largest of the ancient centers among China, Egypt, and Mesopotamia, with as many as 80,000 people in each of its major cities.  Harrapan civilization was located in what today is Pakistan.  We know very little of that society, located in the Indus Valley. It was finally displaced around 1500BC by a group we call the Indo-Europeans.
The Indo-Europeans are the parent group of both those who are in India today and the groups that moved into Europe. We can trace this group in part because of the affinities within languages. Modern languages like Hindi and Urdu in India are distantly related to European languages like French and English. We can thus infer that a nomadic group of people in the area of north of Turkey (southern Russia) distributed themselves throughout Europe, Turkey, Persia, and India. 
2. Around 1500BC, these Indo-Europeans moved into India, speaking an Indo-European language known as Sanskrit. This was the written language of the priestly class, and they produced the classic scriptures of Hinduism, the Vedas. These "Aryans" are known for their caste system, the dividing up of its people into various fixed social layers. 
The indigenous Indus Valley people probably continued on as the lowest caste of the new India, the untouchables. At the top of the caste system were the Brahmins, the priestly caste, with the warrior caste right under them. The majority of Indianas were the Sudras, the servants. Then right above them were landowners and merchants.
3. The period from about 1500 to 150BC is often called the Vedic period of Indian history. The early part of this period was a time when the Hindu religion dominated, a religion that started out as polytheistic (many gods) with sacrifices and all. In later development, it is often thought of as a more of a pantheistic system (everything is god). Reincarnation is often associated with Hinduism, as one comes back from death either higher or lower in the hierarchy of life, depending on how one has lived in the previous life.
It was during this period, in the 500s BC, that Siddhartha Gautama (the "Buddha") would originate what would become Buddhism. He taught four noble truths--1) that life is suffering, 2) that suffering comes from our desire for pleasure and fear of pain, 3) that suffering can be ended 4) by following the eightfold path of a) right thinking, b) right intention, c) right speech, d) right action, e) right living, f) right effort, g) right attitude, and h) right concentration.
Another variation on Hindu religion was Jainism, originated by Mahavira at about the same time. Both of these new religions emphasized that suffering stood at the essence of human existence. But that one could move beyond it.
4. The Persians took over India from the time of Darius I in around 530BC till Alexander the Great in the late 300s. After that point there was the rise of the Mauryan Empire (322-185BC). The founder of this dynasty was Chandragupta (ruled 322-298) who reclaimed northern India after Alexander departed. Then under his son almost all of northern India came under Mauryan rule.
Under Chandragupta's grandson, Ashoka the Great, the empire reached its peak (ruled 304-232). Shocked at the amount of death it took to conquer the eastern part of the area, Ashoka became a Buddhist and founded many Buddhist monasteries. Predictably, his empire declined rapidly after his death and split into several smaller kingdoms. This is the Middle Period of India's history.
5. The golden age of India then revived under the Gupta dynasty (AD 320-550), in large part due to trade with the Roman Empire. I have already mentioned this flourishing of India under my treatment of the Middle Ages.
Next Week: History 10b. Ancient China
 Pakistan was not divided from India until 1947 in the aftermath of World War II.
 In Turkey, they were the Hittites of Genesis 23.
 Most societies implicitly have these sorts of layers, although upward mobility has been more possible in the modern Western world than in any period in history. More than anything else, public education has made this possible.