Bharata Khanda a term used in Hindu texts, describe the geographic region that encompassed the modern countries of Afghanistan, Bangladesh, India, Pakistan, Nepal, Bhutan, Sri Lanka and Myanmar. Most of the kingdoms possessed a main city that served as its capital. Often rivers, mountains and large forests, formed their boundaries. Classical India refers to kingdoms from the 8th century BCE to the 13th century CE. This period begins with Magadha-Pradyota dynasties, lasting 2000 years. This is followed by great southeren dynasties like pallavas and cholas. During this time India is estimated to have had the largest economy in the world.

Kingdoms during Buddha

The most important of these countries was Magadha. To the east of Magadha was Aṇga, and to the north-west was Kosala. To the north of Magadha was Vajji, a confederacy of several tribes, the most important of which were the Licchavis and the Videhas. By the Buddha’s time the Licchavis had emerged as the dominant tribe and their chief city, Vaishali, had become the de facto capital of the confederacy. Wedged between Kosala and Vajji was the Sakyan country, the Buddha’s homeland.
Ajatasatru (491 BC of Magadha empire) — His name in Sanskrit means one who is feared by enemies or invincible. He ruled at the time of Buddha and Mahavira (founder of Jainsim). He started the process of Indian consolidation/empire building that was then continued by his successors. He ruled over a vast part of North & eastern India.

Kanishka

Kanishka of the Kushan dynasty in the second century is famous for his military, political, and spiritual achievements. Kanishka came to rule an empire in Bactria extending from Turfan in the Tarim Basin to Pataliputra on the Gangetic plain. The main capital of his empire was located at Puruṣapura in Gandhara, with another major capital at Kapisa. Kanishka's reputation in Buddhist tradition, as he administered the 4th Buddhist Council in Kashmir as the head of the council. It was presided by Vasumitra and Ashwaghosha. He encouraged both Gandhara school of Greco-Buddhist Art and the Mathura school of Hindu art.

Mauryas

The Mauryan Empire (322 - 185 BCE) replaced the earlier Magadha Kingdom. At its height, the empire stretched over parts of modern Iran and almost the entire Indian subcontinent, barring only the southern peninsular tip. The empire came into being when Chandragupta Maurya build a great empire, after Alexander's departure. He with the help of his mentor the best economist and political teacher Chanakya (Vishnu Gupt) a Brahmin in style and a warrior in his thoughts and the best scholar of those time, united the entire empire and ended the kingdom of Nanda Empire in India. He in fact led a path of pleasing rule and spread his kingdom as far as he could see. He also defeated the Prime Minister of Alexander the Great, Selucas and entered in to matrimonial alliances to strengthen the relation with him. He is considered to be the most famous of all kings in India. His kingdom consisted the main parts of India. He was most probably the first Indian Ruler to unite the emtire empire under his control. He spread his kingdom all over India and to the parts closing in Afghanistan, Asaam and those of South India.
Kautilya or Chanakya), wrote the Arthashastra, a compendium of kingship and governance.
He was followed by great kings, Bindusara and Ashoka. Ashoka is one of the most successful and famous monarchs.
Asoka was greatly moved by the massacre after Kalinga War and he changed his mind and left the path of violence and accepted Buddhism. He then on followed the preaching’s of Lord Buddha. His reign time is from 269-232 BC and his administration area belonged to Patliputra the present Patna in Bihar.The Edicts of Ashoka, set in stone, are found throughout the Subcontinent. Ashoka's edicts (in Prakrit, Greek and Aramaic) state his policies and accomplishments. Ashoka's edicts refer to the Greeks, Kambojas, and Gandharas as peoples forming a frontier region of his empire.
while Vedic, Buddhist and Jain faiths were popular ones, other groups belonnging to ajivikas, atheists, agnostics, and primitive or tribal faiths were sizeable in numbers. Mauryan society began embracing the philosophy of ahimsa (including protecting animals)

Guptas

The Gupta Empire from 320 to 550 CE was an ancient empire founded by Sri Gupta. The empire overed much of the Indian subcontinent. This period is called the Golden Age of India and was marked by extensive inventions and discoveries in science, technology, engineering, art, dialectic, literature, logic, mathematics, astronomy, religion, and philosophy. Chandragupta I, Samudragupta, and Chandragupta II were the most notable rulers of the Gupta dynasty.
The Gupta period produced scholars such as Kalidasa, Aryabhata, Varahamihira, Vishnu Sharma and Vatsyayana who made great advancements in many academic fields. Strong trade ties also made the region an important cultural center and set the region up as a base that would influence nearby kingdoms and regions. Many Indian epics, some from oral versions, might have been written texts around this period.
After the collapse of the Gupta Empire in the 6th century, India was again ruled by numerous regional kingdoms. After Guptas, Harsha established his empire in the 7th century.

Harsha

Vardhan nother Ruler from the northern province of India, whose time reign was said to be in 590-647. He mainly operated too from Punjaab Province of India and almost united the entire place of empire under one. He succeeded his rule after the fall of Gupta Dynasty in India in middle of 6th century. The court of Harsha a center of cosmopolitanism, attracting scholars, artists and religious visitors from far and wide, such as the Chinese traveler Xuanzang. Harsha was a tolerant ruler and supported all Indic faiths – Buddhism, Vedism and Jainism. Harsha wrote – Nagananda, Ratnavali and Priyadarsika. His reign is comparatively well documented, by Bana in Harschacharita and by Xuanzang in Si-Yu-Ki.